All right. Welcome everyone. This is the wide world of WordPress events. And we are here to talk about what WordPress events are, types of WordPress events and what to expect at these events. And we'll share some resources about WordPress events video. My goal is to keep this discussion within the hour. So that said, here's what we won't be talking about today. We won't be talking about setting up a WordPress site or providing support with any WordPress site issues. Because we're here to talk about events. So let's get started. What are WordPress events? What do we mean when we call, when we say WordPress events? So to put it concisely WordPress events are where WordPress people can connect with each other, learn together and contribute to the WordPress project. There are many types of official WordPress events. So these include the most commonly known meetups and word camps. There are also contributor events. There are kids camps. They're the hackathons that we have called do action. And there's also open source workshops. So we're going to take a closer look at these great programs during this session. So first we have meetups. So I'm just curious if anyone in the chat, if you have attended your local meetup group, or if you've never attended one. Feel free to let us know in the chat quite but feel free to chime in at any time so I will hand this over to Devin to chat about WordPress meetups. Alright, thanks Courtney. I believe everyone here has to some extent in WordPress meetup offline or online right. In fact, some of us here probably meetup organizers. So I just like to say thank you so much for growing your community and always making the best effort to gather WordPressers in your area. Currently we have about 700 chapters across the globe. WordPress meetup is a local end that we encourage WordPressers to organize and what we think a successful WordPress meetup is if it happens consistently. So two people gather, talk WordPress and announce it on meetup.com already an official WordPress meetup. So you are free to organize this event and everyone is also free to join and attend. You probably are more familiar with a lecture type of WordPress meetup event. It's actually an event that you can experiment with. You can have a round back discussion or a co-working or a workshop. You can teach how to create in or themes or blocks these days right. You can also, you know earlier, Courtney mentioned about do action. You can actually organize a WordPress in do action format. So there's a lot of options and I believe that you can try organizing WordPress meetup. In fact, recently in Tokyo, folks organized a photo, I don't know how you call it, but you photo hunting. Yes, you do four things where you actually upload and photo walk. That's there you go. So you can upload it to the WordPress photo. You get a badge for that. So it's, there's a long option for you to do that. So yeah, I'm here to represent the project globally that we are doing this meetup reactivation project. So O'Neal here from the Philippines who has been supporting the project where there's still a lot to do because still many dormant meetups but the challenge now is also keep these reactivated meetups to stay active. So if you have any ideas you have any concerns, right, please let us know and let's let's work together to keep our community active growing. Yeah, back to you Courtney. Great. Thanks, Devin. Yeah, so as Devin mentioned we have the meetup reactivation project. And if there is no local meetup group in the area you can always apply to start one. And we share those links for you in the chat, that link. Excuse me. And feel free to share this with folks too. Oh, the chat is a disable. I just got a message from O'Neal. Hence we see a quiet chat room. Let me chat. Yeah, this is, oh, there we go chat. Can anybody start at us on the meeting chat. Sorry about that folks. I'm so sorry about that. Keep chatting. Yes, keep chatting. Yeah, we had a little bit of a zoom hiccup because zoom updated recently and all the city recently. Okay, so thanks for your patience there folks so we're going to move on to talking about WordPress, or word camps, excuse me. So word camps, what are word camps they are informal community organized events that are put together by WordPress users just like you. Everyone from casual users to core developers participate share ideas and get to know each other. And so what makes this different from meetups is that they tend to be larger events with more attendees, multiple sessions and sometimes over multiple days. So I have a question for everyone here. Have you tended a local work camp, or have you traveled to attend a word camp, or both. Please let us know in the chat. I'd love to hear from you. I know that there are quite a few folks that are present that have probably done both. I would say O'Neal just attended his very first in person meetup last weekend. That's great. Yeah, it's been a while since I've been to in person meetup myself. And those are starting up again meetups have been largely online for the past few years because of the pandemic so and let's see black aces haven't attended any yet. I'm glad you're here so you can learn about events. Now goes first in person being post COVID was in December and another one coming up at the end of this month. Fantastic. Yeah, the last word camp I went to was word camp us, which was in San Diego in the fall last year so let's move forward here. So let's talk more about word camps. The first word camp was in 2006 in San Francisco. Were you there now. Yeah, I think I volunteered. Oh, you were there. Maybe 2007 I was there but probably. Yeah, and it was small. I mean the first couple word camps were small is just this room full people that you see in this picture here. And a very young looking Matt Mullen leg here. So that was in 2006 and over. I think this number is probably outdated now over 1100 word camps have happened worldwide since then I know that we've had a few since I created this presentation. And just a fun fact that I wanted to share with you all. So the types of work camps we have we have our local word camps so these are the word camps that gather a local community, and sometimes with visiting speakers so they highlight their local WordPress people there. These are the bulk of word camps that you'll see listed on the word camps schedule so that's at central dot word camp.org right. Let's see we could share that link with you. Thank you. Thank you now go. And on the right we have a picture of an example of a flagship or regional word camp. That's word camp Europe. So all flagship and regional work camps are word camps are on a much larger scale than the local work camps. The one on the left there was a word camp Ferrari and like 2017. And it's in Bob ways that was like about 75 attendees. The photo of word camp Europe on the right there was over 2700 attendees. So both of these are word camps, and both are valuable resources for the WordPress community. So both word camp Europe, as well as word camp yes that I mentioned a few minutes ago those are the well known flagship word camps, but this year the very first word camp Asia will take place. What happened to have some of the organizers here from word camp Asia so now could you tell us a little bit more about what folks can expect at word camp Asia. So our camp Asia is happening this February in Bangkok, Thailand, the dates are 17th to 19th February, and it was cancelled in 2020, the first word camp cancelled by COVID-19, but we are regrouping to host this first flagship event in Asia. The reason why we are organizing this, despite, you know, we've been, I've been to US Europe inspired and the idea of Asian word camp flagship word camp came together, because many of the attendees have a unique barrier to go to word camps in European US visa issues, time, money, and time zone even you're joining live stream. So we wanted to create a place for Asian attendees to be easily be able to gather. So our goals are to make it like a community event that inspires Asian community to grow even further. So yeah, that's the goal. And if you are joining, that would be great. And we have O'Neill also is an organizer who's joining here and Hajime is one of the speakers panel discussion speakers. So we'll see you there. And if you're not coming, you can watch us live stream three tracks are going to be live streamed real time. So this time zone friendly time. Fantastic. Yep. Great to hear that. Well, thank you. Thanks, Nako. Looking forward to that. Especially live stream. I'm glad that there will be one. And I will attend to the ones that I that I that overlap with my time zone. Yeah. All right, so back to just talking about word camps in general I'd like to share a typical word camp schedule with you so usually it looks something like this. Begin the day at registration to pick up your badge and possibly some swag. So if you have time before opening remarks, you can browse the sponsor area and say hello to folks that help make word camps happen. And usually the first official session of word camp is usually a welcome and opening remarks from the organizers. So they will tell you what to expect over the course of the word camp where to go and what to do, etc. And then everyone heads into morning sessions these are typically 45 to 60 minutes long with some brief breaks in between each session. So some word camps will choose to have multiple tracks of sessions so sometimes you have to make a hard decision on which session you want to see at a particular time slot. And then after morning sessions comes lunch. If your word camp is a day long word camp. All day long word camps will be providing lunch for their attendees and that's included in the ticket price. Sometimes that means the meal is catered by the venue but sometimes you'll see food carts, or food, food trucks at word camps, or you'll see some word camps giving attendees a gift card for a nearby lunch spot. After lunch the afternoon sessions will take place similar to the morning sessions until it comes time for closing remarks. Closing remarks are a nice opportunity to recollect ourselves wrap up the day and thank everyone for for coming. And finally most word camps choose to host an after party once the day has concluded again this is all included in your ticket price. It can take many different forms it can be as simple as a happy hour hosted at the same venue. Or you can be having snacks or drinks at a nearby restaurants, or even a fun activities such as a museum or a musical performance it's all up to the organizers. After parties are of course a great place to meet and network with other wordpressers. So what kind of sessions will, would you expect at a word camp. So sessions can take many forms. They can be presentations or lectures, including lightning or flash talk so these lightning or flash talks are short presentations that are usually just a few minutes long that cover a single specific idea or topic. I think the longest I've seen a flash talk or lightning talk is like 15 minutes at most. Another example of a session is a panel or a round table discussion or interview or AMA which means asking me anything where folks sit down at the at the front and just answer questions. No particular like presentation. And so that's a great opportunity for folks to connect with the presenter. There are also workshops as well as networking events. Any of these will make a valid for camp session. Has anyone seen any other types of unique sessions at word camps. Other than you know what we see here listed as examples here. I'm trying to think it's been a while so like, what's a, what's a cool event. Can you, you to think of any quiz, maybe. Yeah. No quiz.  Yeah, as long as it's word WordPress related it, it will count. Quiz sounds fun. I would totally do that. Aside from sessions. What else can you do at a word camp. Aside from, you know, just sitting and watching talks you can browse the sponsor area. And at the beginning, those are the sponsors are the folks that help make word camps happen. And they often have resources to share as well as swag so everyone likes to go around and collect all their goodies from their from the sponsors. There are often what we call happiness bars or help desks at many word camps where you can go and get help with WordPress from folks in the community. There are social events like the after party sometimes if a word camp is on a weekend or if it's multiple days, sometimes there are outside activities that that people choose to do. And finally, what we call the hallway track is the most popular track at a word camp. It's where folks hang out in the hallway like you see here and just chat and network with each other. It is one of the, like I said one of the most popular ways to spend your time at word camp. And I think that's all we have on word camps and I think we're going to go move on to computer events and I'll hand this over to now go. Yeah. Yeah, it looks like a photo that I took. So, yeah, contributor events are one of my favorite part of world camps. And this is a place where you join in usually in like this kind of classroom or like workshops set up, and you sit down, open your computer, or you sit down to chat and work on WordPress project as a contributor. But even if you've never done anything like that, it's a great place to find out what the contribution is about and learn from someone in person. So that's a great opportunity for you to just come show up and learn about what it's all about. And if you're more experienced contributor, this is rare opportunity to meet in person and talk about the work you've been doing. So that's why people really like joining and meeting people because during sessions you don't get to talk to people so much. And this is a good way to get connected and network also. There are, there are, there can be standard events or part of WordPress or WorldCamp or Meetup events. And when it takes place, it usually is called contributor day, but sometimes they have accessibility events or translation event. So it could be any name, it could have any name. There are 21 different teams that you can contribute as part of open source project, and you will whatever skills or experience background you have, you are sure to find a team that you can contribute to. So don't be afraid and come join. And yeah, there'll be a contributor day at WordCamp Asia, is that right? Yes, yes, we are expecting 600 or more people. Oh, that's great. And how many teams will be represented? Yeah, over 21, as long as we can find who we call table lead, someone who teaches how, so over 20 hopefully. Fantastic. Oh, thanks, Nako. So next we have youth events or kids camps and we have Devon to talk about that. So I have actually never been to any kids, but this is something that has been experimented done in, I think, America and Africa. I'm not sure whether we have done it in Asia. This is an opportunity for folks who are interested in investing in the future generation of pressers in your area. So as contributor day, this can be attached to the local WordCamps or it can be a standalone event where you safely introduce WordPress to kids. The curriculum or the content would be based on the ability of the, I would say facilitators or interests of the participants in your area. So it's a kind of casual event, more about engaging the younger generation, the future generation, the young folks of pressers in your area. So yeah, if anybody has tried this in your local community, or thinking about organizing one, why does no, it will be great to hear that these folks trying to invest in the future generation of WordPress. Thanks, Cornie. Yeah. Oh, you know that. Yeah. Yeah, mostly heard about them in North America. Here's an example photo here from WordCamp Phoenix. This was probably, let's see, 2011. So that's like almost 12 years ago. These kids are probably young WordPress professionals now.  I've seen, I've, I didn't attend, but I observed a kids camp. I think it was in Miami and seeing what they do with it is a lot of fun. Yeah. So next type of event that we have is called do action. And so these are hackathons that are organized by the community just like meetups and word camps. So these events focus on using WordPress to give charitable organizations their own online presence. So each do action event will include participants from the local WordPress community that come together to create and build brand new websites for a number of local organizations in one day, usually one day. So it's a full day event. So the goal of do action is to support these charitable organizations by giving them a fresh and dynamic online presence. This enables them to get on with the work that they already do so well without basic website management getting in the way of their productivity. So these are very worthwhile events to go to. Fun fact that I learned last year. So why is this called do action. So with do action being a WordPress focused event and made sense for the name to come from WordPress itself. Do action is a function that is used throughout WordPress core and the name of the function really fits well with the goal of the events to allow the nonprofits to ramp up their own activity and really get down to business. And I think this is our last type of event. This event is structured to open source workshops so we don't see this as often so it's probably the least known event that you see happen but open source 101 workshops spread knowledge and understanding of the open web and open source through these two hour training events. These events are financially supported by the WordPress foundation and their staff and organized by local communities. The workshop is available on learn WordPress so learn dot WordPress dot org. And that is there along with a lesson plan for people to use in their local communities. So as Devin mentioned earlier you can run this as a part of your, your meetup event or your meetup group, excuse me. But if you do.  And we have a quick note on pandemic guidelines. So now go to you. Can you share a little bit there. Sure. So, I just pasted in a handbook page. So, basically, this has been changing over the time but right now at the moment. The guideline is to basically for the local rules. There's no restrictions from the community team or to not have events or to wear masks or having vaccination. It's not required as long as you follow all the local rules. So, yeah, just to be careful but the community team is happy for people to meet in person as long as it's safe in that scenario. So, but we still encourage providing masks and hand sanitizers on the venue and as part of swag packs or press community sport will provide a sticker to indicate, you know, if you want you don't want to be near people without mask. People can wear that sticker to signal their preference. So that's basically what it is. Thank you. And finally, there are many ways to get involved with WordPress events. So how do you do that. You can just attend that's getting involved with WordPress events. Of course, WordPress events like meetups are largely free. You have tickets at an affordable price to cover their expenses. And that depends on the the local currency on what the cost is going to be but we try to the community tries to keep it very affordable for people. You can become in skills to share you can become a speaker you or you can volunteer to help at an event. You can even become an event organizer so you can find more information at make dot word press dot word slash community about all the ways that you can get involved with WordPress events. But yeah the first step is just to attend see you see how that feels for you and volunteer be a speaker. And if you have any questions about them to that WordPress community will be very happy to have you. Oh, something I want wanted to mention one more time. And if definitely if you had any more information to share on the meetup reactivation project. I think there was an update on that last month or something. Yes, we are actually sharing sort of like status updates of the reactivated. But these would be an ongoing projects because we would call it still lingers a little bit here and there and new variants we need to be in full of folks who are probably not comfortable. So, what I wanted to say when we say about reactivation is not we're pushing people to meet offline like a son, but we also appreciate if you keep your community active by meeting online, and we do have a discount that we can share with you all to do that. And it can host to 100 people. And if you feel so thinking of moving forward me person and it's a very new support, you can also and ask a, you can there's a form that you can and then reach out to us and as a message and email to support at what cam.org. If anything you wanted to share with us you need our support anything to keep your community active again and it about meeting as what pressures. Thank you. And now goes shared to the email to the community team there in the chat so thank you. So I think we went we motored right through our content there so we're at the end of what we had to share with you. I'm curious if there's anything new that you've learned today as an attendee to this workshop today. And if you'll be attending a WordPress event soon. I know that now you'll be at WordCamp Asia and O'Neill. Folks if you're attending your local meetup. I'd love to hear if you'll be attending soon. Or if there's any of the events types that we mentioned during this presentation that sounded interesting to you and you'd like to see happen in your local community. So it's going to be your first word camp. I find that hard to believe but I mean also share a few things we also have local words. Kind of mushrooming. We have a lot in India. There's in Kathmandu in Indonesia one grassy. I think in before right before what can Asia with what can she do in the Philippines. And then after that we'll have what can Kerala in India. And then there's more occasion coming in at the moment and in pre planning stage. So what I'm trying to say is, we have a lot of local word camps and if you have the chance to attend and and as Courtney mentioned you can attend you can on tears as speakers, or in fact you can join the organizing team of your local word camps, or just pick a one day organizer which we call volunteers for organizers you probably need to meet your time before the camp before the events, but it's volunteer you can commit to contribute only that particular day what can date. So check out the link that I think earlier Courtney also shared. So it's what can think that was I'm going to do it again later. And also talk with local meet up organizers and sources get together to organize local work camps with your meet up organizers if you're not yet joining the meet up groups. I was just reading a comment in the chat from Richard that this was the same time as the Seattle WordPress group so it was assuming that they were rebroadcasting this. I am. I'm not sure. Sometimes I know that some meet up groups do play videos of other workshops at their media group but you know with over 700 meet up groups in the world. I think that sometimes events are going to overlap. Unfortunately, but thankfully we record ours. The ones that we have on learn WordPress. So another thing is a lot of what can WordPress events are published or like announced on the WP dash admin dashboard. So check out that there's this plugin the event plugin that you can see on your dashboard and see I think the nearest WordPress meet ups or what's happening in your area. Great. I think I shared a screenshot earlier of the, the meet up. The WordPress meet ups, but here is the site meet up comm slash pro slash WordPress. These are all of the WordPress meet ups around the world so I just did say over 700 we have 780 groups now and over 500,000 members worldwide so that's really impressive. Yeah. And you are all of it. We are all part of it. Mm hmm. Now what's the name of it. 500,000 people Wow. 113 countries, still none in Antarctica. I always look down there. We used to have up here in Greenland I thought we used to have one but probably no longer. That was just a fun little diversion there. So something I want to mention is that we have this survey for for everyone that attends and uses the resources on learn WordPress. And here is a link here should only take you a few minutes but the so background behind this is that the training team, which is the team that puts on workshops like these does video tutorials that you'll find on learn WordPress as well as courses and lesson plans. This team is currently working towards updating the needs analysis for for learn WordPress which is a free resource for everyone. So this survey is going to be the first phase of this project and it will help the training team as we continue to grow and improve the materials that are produced by the community. So if you can take a moment and let us know, like your learning needs and what, what types of WordPress learning materials are useful to you really would really appreciate your input there and your input will help improve the resources that we have on learn WordPress in the future so thank you if you're able to do that. And finally, I just wanted to say thank you for learning along with us links shared during this session as well as a link to the recording will be shared via meetup.com so keep an eye out for that message. And as I mentioned at learn.wordpress.org is where you can join more online workshops and watch some video tutorials. We're constantly updating that content usually there's multiple new bits of content every week. So, in addition, if you'd like to connect with more WordPress contributors like us. You can join the making WordPress slack and if you have a WordPress dot org account you can easily join and that's going to be at chat WordPress.org. And yeah if you have any questions any input that you'd like to share you can find us in in that slack. Do you have any questions or anything anyone wants to share in the chat before we wrap up for today. Yes, thank you Richard. Thanks for doing the survey that'll be very appreciated. Spread the word to share that with your local meetups and your local WordPress community. Yeah, so that link did not quite work so chat wordpress.org will lead you to the sign up page. This is actually the expanded link. And if you're logged in on your WordPress dot org account that should be a fairly straightforward process. And so news if you're maybe creating an account and you might have forgotten about it it'll tell you that you that page should tell you if you have an account. Speaking of that I will be having another workshop in a couple weeks about WordPress dot org accounts so keep an eye out for that. So thank you everyone for joining. And I think that'll be it for us for today. So thank you. Thank you Courtney and sharing the space. Thank you everyone. See you in the next event. Yeah, thanks Nicko and Devin and for everyone else for being here. Thank you Devin O'Neill for the word the wordpress diversity AIPAC meeting on slide. You see day.


Teimlo i'r ysgolwch i Ynys Gweithio Aelodau Cymdeithasol ym Llywodraeth Cymru. Mae gynnydd eich bod yn ymwyaf i'r gweithio mewn amser yn ymddangos gyda'r gweithio oesol. Yn Gweithio Cymdeithasol, mae'r hyn yn ysgolwch ar gyfer y Llawg Pwyllgor Fwyllgor Cymru, mae'r cyflwytoedd ym Llywodraeth Cymdeithasol ym Llywodraeth Cymdeithasol yn ymwyaf i'r cyfnod. The first two, which preceded our consultation paper, have been hugely important for us in formulating the provisional views that we've put forward in that paper, and it's clear from the programme for this one that it's going to be equally significant as we take forward our work. So, as Jens mentioned earlier this month, us, together with our colleagues at the Scottish Law Commission, published a joint consultation paper, Building Families through Surrogacy a New Law. As we put our consultation paper together, we had some particular aims in mind. The first is that surrogacy has to work best for those who are most closely affected by it. So the children born through surrogacy whose interests must be paramount, women who become surrogates and intended parents. Secondly, the law should take us at the starting point that surrogacy is a legitimate and accepted way of building a family. And then thirdly, we want to create a legal environment that encourages intended parents in the UK to look to the UK as the best place to have their surrogacy arrangement. But we acknowledge that international surrogacy agreements will continue and we don't assume that all domestic arrangements are good and all international arrangements are bad. The picture is much more complex than that. And as international surrogacy will continue, we think the law should support the interests of children who are born through those international surrogacy arrangements. Now our consultation paper is a comprehensive review of the law and I'm just going to highlight some key aspects of it. And I want to stress at the outset that it is a consultation paper and consultation lies at the heart of how we as law commissions work. We have put forward in our paper a number of provisional proposals for reform where the work we've done up until this point and the meetings we've had with a number of key stakeholders have persuaded us to reach an initial conclusion. We've asked open questions when we don't feel an initial view is yet there. But everything we have put forward is subject to consultation and our final recommendations for reform will be based on the consultation responses we have. So our main purpose in being here this next couple of days is to hear your views, to start a conversation which we hope will encourage you to put in a formal response to our consultation paper. So the first aspect of our work I will talk about is our proposal for the creation of a new pathway to legal parenthood. A pathway under which the intended parents will be the parents of the child from birth unless within a short defined period the surrogate objects. Our new pathway will sit alongside the current post birth parental order regime that will continue to apply in some surrogacy arrangements, particularly international ones. I then explain how we've approached the key question of what payments intended parents should be able to make to the woman who becomes their surrogate. And then outline our approach to international surrogacy arrangements and our proposal for the creation of a national register of surrogacy arrangements. But before turning to the first of those topics I want to draw together some of our proposals and explain how we see surrogacy is operating in the UK under a reformed law. One of the things we've been struck by in the work we've done so far is the keenness to ensure that surrogacy in the UK does not become a commercial arrangement. We agree with that to the extent that under our proposals surrogacy organisations will remain non-profit making bodies and surrogacy agreements would not become enforceable contracts. On the topic of payments we have a wide ranging discussion and that includes asking the question whether a woman should be able to be paid for the gestational services that she provides as surrogate. In looking at the question of payments we haven't found the classifications of arrangements as commercial or altruistic to be a useful one. We find that that classification suggests a bright line that simply doesn't exist even under the current law and practice. So with that in mind I'll turn first of all to our new pathway to parenthood and I'll say a few things first about what arrangements will be eligible under the new pathway. We hope that most domestic arrangements will be brought within the new pathway. That includes traditional as well as gestational arrangements. But international agreements will not. That's because our new pathway contains a number of safeguards within it that it wouldn't be possible or feasible to ensure a met in international agreements. For arrangements under the new pathway we've also provisionally proposed that in cases of medical necessity it should not be a requirement that one of the intended parents has a genetic link to the child. That proposal reflects a view that has been made strongly to us in our pre-consultation discussions that in surrogacy arrangements the shared intentions of the intended parents and surrogate can be more important than the genetic relationship with the child. We ask whether other domestic arrangements that don't fall within the new pathway should also be able to carry on without a genetic link in cases of medical necessity. But we have taken the view that for international arrangements the requirement of a genetic link should retain. We think there would be an unacceptable risk of child trafficking if it was removed in the international context. So those were a few points on eligibility for our new pathway. Under the pathway the intended parents journey to becoming the parents of the child begins prior to the child being conceived. So as it happens at the moment the intended parents and surrogate would meet, organisations where the licensed clinics or surrogacy organisations that want to help provide matching or facilitation arrangements to enable intended parents and surrogates to meet up would need to be regulator to provide those services and that regulation would be through the HFEA that the human fertilisation and embryology authority. Once they have met there would be criminal record and medical checks carried out on the surrogate intended parents and the surrogate spouse or civil partner. Now that is essentially formalising what often happens in cases in any event. There would also be a requirement that the intended parents and surrogate obtain implications counselling. When they are ready to enter into a surrogacy arrangement they would enter into a formal agreement after obtaining independent legal advice. The pregnancy and childbirth would then happen as happens at the moment. But when the child is born for the moment of birth the intended parents would be recognised as the legal parent of the child. Now we propose as a safeguard that the surrogate should then have a right to object to the intended parents being legal parents which would have to be exercised in a short period of time before the registration of the birth of the child. If she exercises that right to object which we think would only be in very rare cases then the surrogate would become the legal mother of the child and the intended parents could then make an application to court for parental order as happens under the current regime. Now we think that right to object provides an important safeguard and is required to both respect the rights of surrogates and to respect requirements of international law. In putting forward this new pathway to provisional proposal we believe that we have proposals that accord with what surrogates and intended parents all wish to happen under UK law. We have in particular been persuaded by the views of women we've met who have been surrogates who have said to us that they don't agree with being recognised as a mother of the child under law because that's not how they see their role. We think it's important that the law respects and reflects the autonomous decision made by a woman who becomes a surrogate and that the focus of the law should be on ensuring that the decision to become a surrogate is a fully informed one and so we're pushing back that regulation to the preconception stage. But we would not put forward this proposal unless we were convinced that it was also in the best interest of the child born through a surrogacy arrangement and we think the best interest of the child are served by the law reflecting the reality of his or her parentage at the beginning from birth. Now as I said the new pathway will sit alongside the parental order route that will remain for some agreement so I'm not really going to talk to this slide but it summarises the different features of the new pathway and the parental order route particularly at the time at which the intended parents are recognised as the legal parents of the child. So I'll turn next to the issue of payments that the intended parent should be able to make to the surrogate. This has proved unsurprisingly to be one of the most contentious issues in the discussions that we've had so far and we've heard views from people across the spectrum as to what payment should be permitted. At the moment UK law says that the surrogate can be paid only her expenses reasonably incurred but there's a recognised lack of clarity around what expenses covers. We've taken the view that it's simply to open ends of the term it means different things to different people and so rather than approaching the topic by trying to clarify what expenses means we've taken a step back and we've identified a number of different categories of payments that the law could permit and we asked for views both on whether those categories should be permitted under UK law and what payments would fall within each of those categories. So I'm just going to outline them without saying much about their content. So we begin with the narrowest category of essential costs relating to a pregnancy. So costs that would do no more than ensure that the surrogate is not left financially worse off as a result of being the surrogate. We then ask about additional costs incurred through the surrogacy. Now by calling these additional we don't suggest that they are less important to the surrogate but it's an acknowledgement that there are some costs that do not need to be incurred however useful and beneficial they are. We then identify a category of costs that arise specifically because the pregnancy is for the purposes of the surrogacy arrangement. So costs that would not be incurred where a couple are having their own child together who they will raise. Now for those three categories we ask an overriding question as to whether money paid under those categories could be by an allowance or should only be payable against receipts. We then look at lost earnings. We look at particular issues that arise over the impact of payments to the surrogate on entitlement to social security benefits under UK law. We then have categories for compensation for pain inconvenience, medical complications and death. We discuss gifts that the intended parents make to the surrogate. And then finally we ask if the intended parents should be able to pay the payer woman for being their surrogate. And by this we mean specifically pay her for the gestational services that she provides. Importantly we make clear that any such payments could not be dependent on the surrogate giving birth to a live child or on agreeing that the intended parents should then raise that child. We ask whether if these parents, if these payments are permitted, whether they should be open to negotiation between the parties or they could be capped at a fee set by the regulator. So that's the approach we have taken to the issue of payments. Moving then to international surrogacy arrangements. These arrangements of course raise particular concerns because the absence of international standards means that the measures in place to protect women and children involved in surrogacy in different countries varies to such a significant extent. We're all aware of the significant concerns of exploitation that have arisen in some jurisdictions. As I said at the beginning, we hope that bringing clarity and certainty to UK law will remove some of the incentives that intended parents have to enter international arrangements, but we acknowledge that international agreements are going to continue. Now, intended parents who have used international surrogacy are often expressed their disappointment that legal parentage that's granted to them in the country in which their child is born is not recognised in the UK. So that even if they arrive in the UK with a birth certificate in their name, they still have to make a parental order application. We've taken the view that the concerns of exploitation in international surrogacy agreements and the inability of UK law to impose effective safeguards on women in other countries who become surrogates for UK parents dictate against the blanket recognition of legal parenthood granted overseas. But what we suggest is that the Secretary of State should have a power to recognise legal parenthood that's granted in other countries and that that power is one that should only be exercised where the Secretary of State is satisfied that the protection provided to women and children in that country are of an equivalent level to UK law. Beyond that, our focus in international agreements is on considering the operation of nationality and immigration laws and looking at how they might be improved so that parents who have a child overseas can more quickly bring the child back into the UK. We've heard of instances where intendor parents have had to spend several months in another country where their child has been born and we don't think it's in the best interest of the child for that to be happening where the parents often don't speak the language, have no support network and have no access to medical care if they're concerned about the health of the child. So, finally, I'll say a few words about our proposal for a national register of surrogacy arrangements. One of the issues we've been concerned with in drawing up our proposals is to ensure that children born through surrogacy have access to information about their genetic and gestational origins. We provisionally propose creating a national register of surrogacy arrangements to record for each child born through surrogacy the identity of their intended parents, the identity of the surrogate and information about any gamete donors. We also ask whether non-identifying information about the intended parents and surrogate should be collected, which already happens in the case of gamete donors. Now, how that information reaches the register would depend on the type of surrogacy arrangement. If it's onto the new pathway, it would be sent to be registered by the regulator surrogacy organisation or licensed clinic. Onto the old pathway, it could be gathered through questions asked on the parental order application. There should note that we do also say that any information registered would have to be verified in order to do so. If non-identifying information is collected, we suggest that should be accessible to the child at 16, identifiable information would be accessible at 18. We also consider who else might want to have access to the register to identify people if they all want to meet up. We have in mind here, for example, children born through the same surrogate who have a genetic relationship to each other although are not born for the same intended parents. We also ask if there might be an interest in children who are born through the same surrogate but who do not have a genetic relationship to each other may still want to be able to find each other and meet up. So, looking at that perhaps unexplored relationship of children whose only connection is that they have been carried by the same gestational surrogate. So, that is a whistle stop tour. I set a Yn's 500 pages in 15 minutes. I'll take a deep breath at the beginning and see what came out. I hope it gives you a flavour of what we have said. There are a number of people from the teams at the Law Commission here for the conference so please do talk to us over the next couple of days. Thank you Yn's.


We will get started with the lecture today. So, we will just take a quick recap of what we studied in radiation 2 yesterday. We said that there is a black body and the black body what is the nature of the black body? Black body has three characteristics. One is it is a perfect emitter, perfect absorber and it is diffuse. It has no preference for direction. So, and then we said that the emissive power of a black body is given by sigma t to the power of 4 and this is what is called a Stefan Boltzmann law thanks to the efforts of both professor Stefan and professor Boltzmann. So, this is the relation which was given by Boltzmann and I mean derived by Stefan and Boltzmann. Boltzmann, Stefan found this by experiments that is simple empirical correlation, simple curve fitting, but Boltzmann did the derivation of sigma to get a get us 5.678 into 10 to the power of minus 8. Otherwise, that constant was obtained through theory, but the beauty is that the credit goes to Stefan because he chose t to the power of 4 that is the major credit. The power 4 is given by Stefan and 5.678 into 10 to the power of minus 8 theoretical derivation is given by Boltzmann. The very fact that Stefan had the ingenuity to choose t to the power of 4 that is where his contribution comes. The very fact that the heat transfer the delta t it is the temperature difference is not no longer linear in case of radiation he had perceived that through that relation. That is the beauty of empiricism. People make a criticism always that oh no this guy has done experiments and just given the empirical relation only when you make an observation you can start thinking of explaining it. If there is no observation how do you explain it? So the first thing is first step in research is that one has to go and make observations. Something is decreasing something is increasing now we will start thinking how do we explain this increase or decrease that is how the research progresses. So we should not be criticizing people who are making observations and giving us correlations. But if we should we should criticize those people if they do not explain it to us those correlations. So we should try to make an attempt to explain the experimental correlations whatever we are arriving at in whatever research we are doing. So then the cavity can be visualized as a black body black body if the cavity is a perfect absorber and then emitter. And spectral black body emissive power is the amount of the radiation energy emitted by a black body at an absolute temperature T per unit time per unit area per unit wavelength this is what is Planck's distribution. And we have Planck's constant and C naught do not forget this C naught. C naught is the mother of all everything here. The very fact that C naught you see here that itself suggests that my electromagnetic wave is nothing but light that itself suggests that it is light. So it is the velocity of light in vacuum 2.998 into 10 to the power of 8 meters per second. So k equal to 1.3805 into 10 to the power of minus 223 joule per Kelvin universal Boltzmann constant. Now you can see Boltzmann's why it is called as Boltzmann constant. So Max Planck did this and we if we put emissive power for a black body which is pi I b because it is a diffuse emitter. So I get pi I lambda b. So if I substitute that I get new constant C 1 and C 2. C 1 equal to 3.742 into 10 to the power of 8 watt per meter to the power of 4 upon meter square C 2 equal to H C naught by k equal to 1.439 into 10 to the power of 4 micrometer Kelvin. Now this is the Planck's distribution what we have. So I implore that in your classes you spend enough time in distributing this Planck's distribution. So this is emissive power this is wave length area under each curve gives me the net emissive power of the black body at that temperature. This is 100 and this is 5800 why we have plotted 5800 because that is almost equal to the sun's temperature that is why it is called as here it is written as solar also. So in fact I would request that you should you should request your students to plot this in excel sheet we are not copy pasted this figure from any textbook we have plotted this in a grapher and drawn this graph. So this so if you plot it yourself you will feel the numbers much better than otherwise. So you have the emissive power and wave length and there is always a maxima if I connect that maxima you get lambda maximum into t equal to 2897.8 micrometer Kelvin. So this is what is called as Wien's displacement law. So he is Professor Wien and if I integrate this with respect to all wave length covering all thermal radiation wave length I will be getting sigma t to the power of 4 where sigma is 5.67 into 10 to the power of minus 8 watt per meter square Kelvin to the power of 4. So that is Stefan Boltzmann law in fact in fact there is a paper on the history of Stefan and Boltzmann I will I cannot upload the paper myself but I will try to make a notes please note this down I will try to make a notes on Stefan Boltzmann but I can give the reference. So that might be available in if the journal paper is available at your end download that paper and read it gives us the historical perspective of how the Stefan has done the Kharu fitting it is a beautiful paper I would recommend that all teachers should read that paper if you do not have that paper you send me you send me a you send me an I will make the notes and send because I cannot upload the paper PDF paper I am not supposed to give because of copyright issues I cannot give that journal paper if you can download from your end you can always download so then we studied band emission f of 0 lambda equal to e lambda, b d lambda 0 to lambda upon sigma t to the power of 4 so if I put that I represented that in terms of lambda t and we said that if I have to know the fraction of the energy or the fraction of the emissive power which is emitted within a band of 0 to lambda 1 if I need that I have defined what is called as f of 0 lambda this is represented in terms of lambda t and I have i lambda, b lambda t upon sigma t to the power of 4 and this is i lambda, b lambda t upon i lambda, b at lambda maximum, t okay so with this we solved a problem and we appreciated the importance of this table very much and then we went ahead and defined 4 emissivities that is this is the emissivity in general is the radiation emitted by a surface upon radiation emitted by a black body at the same temperature so that is why the emissivity the spectral emissivity here you see the emissive power of a real body is lower than the black body number 1 and number 2 is that it is having directionality unlike a black body so that is the real surface. Now we defined 4 emissivities one was spectral directional emissivity and total directional emissivity and spectral hemispherical emissivity and total hemispherical emissivity so we said that whenever directional dependence is there directionality I always handle it by intensity whenever directionality is not there whenever I have averaged the intensity over all directions then when there is no directional dependence I handle emissive power that is what we see here whenever directional dependence is there spectral directional emissivity you see theta comma phi I am using I I lambda comma E lambda theta comma phi t upon I lambda comma B lambda t okay so next is I get total directional emissivity that is I have again directionality so that is why I have intensity again so then spectral hemispherical emissivity here I have come back to emissive power because I have integrated over theta comma phi emissive power at lambda given by lambda at lambda comma t upon E lambda comma B lambda t we related spectral hemispherical emissivity with the directional emissivity so when we do that we get some equation like this and the next one is total hemispherical emissivity that is emissivity equal to E of t upon E B of t and of course you can represent this as epsilon lambda lambda t E lambda comma B lambda comma t this is what we had defined just little while ago that is this so if I substitute this this is what I get applying this relation I solved a problem this is what applying this is the application of that relation I solved a problem where in which I have taken for this bandwidth that is 0 to lambda 1 I have epsilon 1 and between lambda 1 to lambda 2 it is epsilon 2 and between lambda 2 to infinity it is lambda 3 that is why I get epsilon at what is this I said average emissivity what is this actually this is spectrally averaged perhaps if it is nothing is mentioned perhaps it is perhaps it is hemispherical emissivity it is averaged that is why we have put average so do not get carried away average it is actually spectrally we are averaging right now and it is perhaps the hemispherical emissivity so I get epsilon 1 f 0 lambda 1 t epsilon 2 f lambda 1 to lambda 2 plus f plus epsilon 3 f lambda 2 to infinity how do I get f lambda 1 to lambda 2 it is f 0 to lambda 2 minus f 0 to lambda 1 if you see one another thing I want to tell is we all think through images another insight what I have learned with time is that whenever I tell something what should come in the back of my mind is the image so when I say f lambda 1 to lambda 2 equal to f 0 to lambda 2 what is the image which should come to my mind is that my image should be I should visualize that and tell otherwise perhaps I am not telling with that feel that is this is the emissive power and this is the lambda when I say lambda 1 to lambda 2 this is lambda 2 and this is lambda 1 so that is f of lambda 2 to lambda 1 mean it is f of 0 to lambda 2 minus of f of 0 to lambda 1 so the point is what I am trying to say is we all think through pictures actually see that is what always everyone tells see when I always take this example that is whenever I remember my mother my mother's face comes to my mind so whenever I remember a concept a figure should come to my mind then only I have understood that concept if I cannot if I cannot get an image when I see a concept then perhaps I have not understood that concept so whenever a concept I explain it should be through an image and that image should be recorded in my mind if no image is recorded in my mind I have neither I have not transmitted that concept to my student and nor I have understood that concept myself so we have to my point is we have to transmit concepts through images through figures through figures through figures figures tables graphs these are the ones which we will remember very easily you see I think as teachers you all appreciate you may not remember these names of your students but definitely you remember their faces when it comes to you will say oh I have taught you but you will vaguely remember him but you will not remember his name that is precisely what I am saying so we all remember images we may not remember exact relation but we will remember concepts through images that is what that is what we need to we need to emphasize while teaching. So that is what we did epsilon 1.3 epsilon 2.8 and 0.1 we did that integration and we get we got the value the total emissivity total hemispherical emissivity we got it as 0.521 so there is another problem I am sure many enthusiasts would have solved that problem yesterday night so now let us get move on to how does real surfaces do not emit radiation now real surfaces do not emit radiation in a perfectly diffuse manner because they are not black bodies they have directional dependence so whatever grass I am flashing I am not going to reason them out because it is quite difficult to reason them out I will attempt to reason them out in the second half of today's lecture so please do not ask me questions for now why is emissivity increasing decreasing either with temperature or with direction all that I can say for now is that they are all dependent on electromagnetic permeability and electric permittivity okay so they are dependent on that whether it is a solid liquid gas so it is they are all dependent that is emissivity transmissivity reflectivity absorptivity all these are dependent on electrical permittivity electrical conductivity magnetic permeability and the charge of the electron so with and the velocity of speed a velocity of the electromagnetic wave in that medium if you remember I had put c equal to c0 by n what is that n what is that n refractive index so we are going to define in the second half refractive complex refraction index equal to refractive index minus ik where is absorptive index so this n and k that is what is that I said complex index of refraction is given by n minus ik that is m equal to n minus ik where n is refractive index which we have studied through Snell's law I will touch that in the afternoon k is the absorptivity index this n and k are related by are related are related to electrical permeability and electrical permittivity and magnetic permeability I do not remember I do not remember what is the notation for magnetic permeability electrical permittivity and magnetic permeability okay so why am I telling all this epsilon reflectivity transmissivity absorptivity they are all functions they are all functions of this n and k so that is what I am trying to say I will for simple cases I will try to give you relations between epsilon and n and k in the second half of today I should not get into that now because I have to cover that is little as teachers we should know little bit although I also do not know completely but little bit whatever I have understood from modest I am going to explain you in the second half but now let us move on what we teach in the undergrads so emissivity is a function of direction so this figure demonstrates that the real surfaces are not diffuse surfaces for conductors see I why I said electrical permittivity and magnetic permeability is because this conductors have different electrical permittivity okay so that will decide my emissivity and this emissivity is having preference to particular direction for conductors and nonconductors this is a general way it is not that for all nonconductors it is going to be like that generally for nonconductors emissivity is higher than that of conductors and nonconductors emissivity increases continuously with theta and this is and here theta direction is shown okay theta is 0 means it is normal okay okay so with this let us move on so that is what is called as when theta equal to 0 that is what is called as normal emissivity because it is normal to this surface so now temperature dependence like thermal conductivity here also we have temperature dependence the total normal emissivity as a function of temperature if you see you get that for tungsten it is increasing stainless steel it is increasing aluminum oxide it is decreasing heavily oxidized stainless steel it is decreasing again I will take the recourse of permeability so okay so I have not explained you why it is increasing decreasing I have just stated that emissivity is a function of temperature now and you can see that emissivity of polished metals is generally lower than emissivity of unpolished materials see yesterday for one of the questions of Prof. Vivek I was answering that a diffuse surface a diffuse surface will have I emissivity that is an unpolished is towards diffuse that is there is no glaze if you see in fact in fact if you see the blackboard most of our blackboards which we use they are all diffuse actually because of putting chalk over it again and again they have become diffuse they are not polished so blackboard will be more will be having higher emissivity than the blackboard which I started using on the first day on the first day so polished metals so if you want to increase the emissivity polished metals should not be used they should be used unpolished metals and another thing I do not know whether you have noticed or not so we I think I will come to that example little later on that is I wanted to explain the aluminum foil thing aluminum foil thing I will come to that little later on so these are oxidized metal and as you see here you see human skin and water water is emissivity one I understood this in a hard way see actually one of a one day I had a wonderful student by name Prabhu he was one of the best students I had and he was doing some two phase slow experiments and one we had to heat the water in a tank and we were supposed to take the tank temperature that is the water temperature in the tank to reach to 50 to 60 degree Celsius and then do the experiments by maintaining the temperature at 50 or 60 degree Celsius so I went to lab one day and every day I used to check the temperature of the water in the tank so that I put off the heater or put on the heater by checking with the thermometer but one day I went to the lab and Prabhu was measuring with the thermal camera that is there is a thermal gun see I do not know how many of you why I am taking this example because I want to explain you how does the thermal gun works also so there is a thermal gun nowadays what is that Taiwan make Taiwan thermal guns are available just for 5000 6000 rupees if you can afford I would request you to purchase thermal gun it is actually called as thermal infrared infrared gun also few people loosely call it as camera also although it is not or they call it as thermal infrared laser also okay these are various names there is fluke make if you are very much interested I can give you the address and the supply person of this fluke make you get a simple thermal camera fluke is little expensive means it comes to around 25 to 30,000 rupees if you cannot afford that much we get Taiwan make Taiwan make thermal cameras also so this Taiwan make thing we had which is hardly 4000 5000 rupees Prabhu was just measuring the emissive measuring the temperature of the water with that gun he said temperature is 40 degree Celsius without putting thermometer I used to put the hand gloves and put the thermometer because water was hot and things like that so from Prabhu I learnt that emissivity of the water is one how did I learn that emissivity of water is one because in a thermal gun I should I should fix the emissivity then only I will get the temperature okay so if I know the emissivity of a surface the thermal gun gives me the temperature so on that day he was getting directly the temperature why because the emissivity of water emissivity of water is one emissivity of water is one so he said sir thermometer reading and the thermal gun reading are matching he also did not know that emissivity of water is one but they are matching from that we realize that emissivity is one we refer back to books and we saw that emissivity of water is indeed one in fact yesterday you have taken emissivity of ice also as one okay so the point is what I want to tell is a thermal camera or a thermal gun measures measures the heat flux that is the thermal radiation what is the thermal radiative heat flux what is the thermal radiative heat flux we have Stefan Boltzmann emissive power Stefan Boltzmann law says that it is sigma t to the power of 4 it gives it thermal camera if this is my thermal camera the input is radiative flux that is e that is sigma epsilon t to the power of 4 if I have a surface if it is emitting if I aim my gun towards the surface it is going to capture sigma epsilon t to the power of 4 remember this is watts per meter square watts per meter square that is why I call this is radiative flux so now this gives this gun gives it gets the voltage output this voltage output actually how does it get voltage output again it is a simple resistor which is there inside because of this radiative heat flux it gets this resistor gets heated up because of this heating up the resistance changes and that is change in the resistance is perceived as a change in voltage okay so this is what is called as actually bolometer there is this is what is called as bolometer that is bolometer essentially consist a resistance and when radiative heat flux is incident on the resistance this resistance the temperature of this resistance increases so this change in the temperature is perceived as a change in the resistance which is perceived as a change in the voltage which is what we measure and this voltage output is a measure of temperature how can I get temperature can I get temperature directly here no only if I know the emissivity if I plug in emissivity in that camera it will give me temperature okay so what is thermal camera then what is thermal camera thermal camera is a combination of multiple bolometers that is mult is a combination of micro bolometers thermal camera micro bolometers micro bolometers that is in a thermal camera you have if you purchase a thermal camera or what you most of us have cameras with us in our mobiles how do you specify a camera megapixels you say 10 megapixels I have 20 megapixels I have similarly thermal camera also has pixels pixels means what it is it is made of multiple squares my camera is capturing my image using multiple squares multiple squares so 10 MB pixels means that many squares I have to make my image in fact my image is being transmitted to you through thousands of pixels tens of thousands of pixels that is how each square is a combination to make my image similarly to get a thermal image there is typically if you go to market you get 320 by 240 pixels 320 by 240 pixels thermal camera so this 320 by 240 pixel thermal camera is that means along this axis you may have 320 pixels and here you have 240 pixels that means you have 320 on this direction and 240 squares in this direction so that many pixels you are going to form when you are making a picture thermal picture so each pixel is what here each pixel is a micro bolometer each pixel each pixel is a micro bolometer and each micro bolometer has to be separated from the another micro bolometer otherwise resistances will become one resistance will talk to another resistance so they have to be insulated that is where micro machining comes into picture this is micro in size micro on size this complete micro bolometer will be hardly one centimeter by one centimeter within that one centimeter by one centimeter they have to embed 320 by 240 micro bolometers and again they have to be separated by insulators electrical insulators so that is what is a thermal camera made of so coming back if you have a thermal camera in a thermal camera what is that it will it will give you radiative heat flux sigma epsilon t to the power of 4 it will give you if you know the emissivity of a body that is you take a black paint you take a sheet you apply black paint with lamp that is candle suit that is it you get an emissivity almost as close as 0.98 0.99 of course it cannot be used for high temperatures because lamp black will vanish at high temperature but at room temperatures are nearly up to 70 to 80 degree Celsius lamp black there is no problem so for that body you can take epsilon so then you can from if you get the emissivity if you fix the emissivity thermal camera directly gives you the temperature everyone keeps asking me in our lab if you because we have thermal camera they keep asking us ok you have thermal camera you get me the thermal camera will measure the temperature no it is not like that I should be knowing the emissivity if I know the emissivity only we can measure the thermal camera someone will come and ask me I have a tool rotating and machining is going on I want to measure the temperature come and measure because you have thermal camera that is the perception we have no thermal camera does not give me temperature if I know emissivity only I can measure the temperature now why did I tell all the story I told the story because I wanted to explain you how to measure the emissivity have I explained it I have explained it implicitly let me explain it explicitly that is what do I do I take a thermal camera and now I take a thin metal foil this is thin metal foil thin metal foil and I heat this metal foil there are multiple ways of heating metal foil you can take you can make an iron box type heater using the nichrome heater you can put the nichrome heater behind of course before the heater there should be insulating material and after that also insulating material if you have and if you heat this the metal plate get heated up or you can take the thin metal foil and directly give dc power supply let us say it is stainless steel foil you give directly dc power supply how do you give dc power supply why is it made thin metal foil because I need to increase its resistance r equal to sigma l by a if my cross sectional area is less my resistance will go up still if I have to give direct dc power supply here current will be very large voltage will be very less it is safe way my students can touch the foil I can touch the foil you can touch the foil nothing will happen so because the major culprit in electricity is voltage not electric electrical current okay if the current is high also no problem even if it is 400 amps no problem as long as the voltage is 1 or 2 volts I can touch it there is no problem okay so that is what here we do if the resistance is high current will be very large voltage will be very less you can put a transformer and achieve this inlet to the transformer you can have 220 volts and 15 amps outlet of the transformer you can have high current but low voltage that is one way or you can get directly dc power supplies nowadays what 5000-10000 rupees we will get very good dc power supplies you do not need large power if you take some such dc power supply or ac supply and give directly if it is ac supply it has to be given through transformer or it has to be directly dc supply dc supply means you have to purchase a dc power supply and connect to our ac supply and get the dc okay so if you do any of that why am I doing all the circus because I want to maintain this stainless steel foil at certain temperature at a constant temperature let me say I maintain that at a constant temperature now I will put a thermocouple behind now I put a thermocouple why to get the temperature of this foil so thermocouple temperature I get now I will I will use the camera I will use the camera and in the camera there is a provision that I can change the emissivity I will keep on changing the emissivity until my camera's temperature matches with the temperature indicated by the thermocouple that emissivity what I have set in the camera will give me the emissivity of the emissivity of the surface I hope you have all understood so point is how do I measure emissivity this emissivity is not spectral emissivity this emissivity is perhaps a sort of total hemispherical emissivity because I am covering it I am seeing the camera from all directions so it is sort of hemispherical number one and it is it is not spectral because why it is not spectral because this camera is typically the cameras are between three micrometer to fifteen micrometer typical thermal guns whatever you purchase they are between three to fifteen micrometers why because we you and I know thermal radiation is within this range okay so this range is covered for spectrally averaged between three micrometer to fifteen micrometer in all directions that is total hemispherical emissivity is measured by a simple thermal camera you if you purchase 5000 rupees worth Taiwan make thermal gun you can measure the emissivity you can cook this whatever setup whatever I told now you can build this experimental setup in your lab and cook up one more emissivity experiment I know you measure emissivity in a little different way I when I coordinate when I interacted with the coordinators in the coordinator workshop they have a setup similar to the one which we have based on the heat flux they will measure the they will keep they will take a black body and they will take an ordinary black body ordinary body try to maintain the same heat flux by operating or by changing the temperature and see that at what temperature both the heat fluxes are same and then equate that and then you get the emissivity apart from that this is another elegant way of measuring thermal measuring emissivity this way we would have introduced the student to the thermal gun another application which you have noticed or not this example I always take why because this is very close and we would have all of us would have noticed this that is when swine flu was observed you in NDTV and CBN IBM they were flashing in the airports people were holding the thermal camera people were holding thermal camera and they were seeing the people who are coming through the exit port that is they were seeing whoever is having temperature higher than 37.5 normal temperature they were screened they were taken to the doctor and asked for that means they were trying to see whether a person is having fever or not through the thermal camera the beauty of thermal camera is that it is a non-intrusive measurement now the person who is being measured also does not know that he is being measured okay so such a and another advantage is that the emissivity of the surface is one so I do not have to plug in any parameter in my thermal camera so thermal camera has some tremendous applications in real life but we should keep in our mind what are the what are the limitations of the thermal camera thermal camera does not give temperature that is what we need to appreciate okay so with this let us move on I digressed because I wanted to explain you how does one measure emissivity in fact if you want to get a perfect black body there is there is a paint called pyromark there is a paint called pyromark they have very nicely I do not know the composition of this paint but this paint is a very good paint which can sustain blackness that is the emissivity and absorptivity are closer to one even at high temperature of 1000 degree Celsius but only thing is that we need to bake it that is we need to keep the pyromark after painting for we have to spray paint we cannot we cannot paint it by brush we have to spray paint it number one and number two we have to what is that we have to bake it under furnace for keeping it at 200 degree Celsius for let us say 4 to 5 hours that is that is what is what is called as baking if you bake it with the pyromark under a furnace this will give me emissivity absorptivity closer to one even at high temperatures okay so this also you can do in your lab by putting this okay coming back so these are the range of the emissivities what we get for various materials and similarly we have absorptivity so that is absorptivity and reflectivity and transpecivity this we have defined in the yesterday's class and these are the various definitions I hope you have all gone back and brushed up yourself all these definitions remember that I am using whenever I am using absorptivity I am using the notation I because I have to I have to take care of intensity incident on to my surface so if you note that difference all other definitions are going to be same and absorptivity is a function of temperature and another important thing yesterday one of the professors during interaction asked and I said I am postponing this question that is emissivity sorry absorb emissivity depends on the surface temperature but absorptivity is almost if not completely independent of surface temperature but what does it absorptivity depends on absorptivity depends on the temperature of the source at which the incident radiation is originating okay so why because you see in this example which is shown here there is a house the radiation on to the house is from sun from sun which is sitting at 5788 degrees Celsius and from trees which is sitting at 300 Kelvin okay so what is the emissivity what is the absorptivity of 3.9 what is the absorptivity of sun 0.6 sorry absorptivity of sun is a wrong term absorptivity of my house because of the incident radiation from the sun or because of the incident radiation of the tree because of the incident radiation of the trees the absorptivity of my building is 0.9 on the other hand absorptivity of my building because of the incident radiation of the sun is 5780 absorptivity how have I find absorptivity it is the it is dependent on incident radiation that means it should be dependent on the source not the sink that is the material which is emitting it is not that. So it is dependent on the incident rate it has to come from the definition it has to come from definition if you see how do I define absorptivity absorptivity is the net irradiation on to my surface. So that means it has to depend on the source. So you can answer your students that absorptivity is dependent on the source because it is coming from the definition. So that is how we can answer why is absorptivity dependent on the source temperature but not the sink temperature. So reflectivity similarly we can define reflectivity and I only take reflectivity for explaining reflectivity example yesterday also I took this example in a flask I said that my flask material if you opened it it is very flashy why because I want to have very high reflectivity very high reflectivity and I think you have all noticed we use aluminum foil for packing our chapatis when we go in trains when we are going travelling in train we pack chapatis in and even in train we are served with chapatis which are rolled in aluminum foil why those why aluminum foil why not some other plastic cover why because aluminum foil is having high reflectivity very high reflectivity. So coldness that is against coldness no coldness can seep into my chapatis that is the point that is the point. So no heat transfer is there from my chapatis to outside so that is why we can be high reflectivity example can be quoted taking aluminum foil okay even on even if you see the if you take a pipeline and if you have put thermo wool you have put thermo wool around a pipeline now thermo wool is put to basically control the conduction losses and convection losses. So you have put the thermo wool now over and above this thermo wool you would have seen aluminum foils wound on that okay very high reflective foils are wound on that why because reflectivity is to be avoided okay I mean high reflectivity should be there there is no radiation losses from the thermo wool to the outside atmosphere is that okay okay so with this we have the reflectivity the reflectivity is defined there are two ways of looking reflectivity one is a diffuse surface another one is specular specular is like mirror that is whatever angle of incidence is equal to angle of reflection so if that is the case then it is called specular otherwise it is diffuse that is it is equal in all directions so we have trans similarly we have transmissivity all sorts of definitions spectral hemispherical total hemispherical and other definitions we can go ahead and define this is just I do not want to spend time here why leaf is green I think we all study this in plus two because it absorbs all other colors except that it emits only the green color I think we say this again and again so I think I will just solve this problem before I sign off okay so I have spectral hemispherical absorptivity this is the problem how does spectral hemispherical reflectivity vary with wavelength and what is the total hemispherical absorptivity of the surface if the surface is initially at 500 Kelvin and has a total hemispherical emissivity of 0.8 how will its temperature change upon the exposure to the irradiation so what is given I have been given the absorptivity what which absorptivity I have been given spectral absorptivity that is up to 0 to 8 I think if I am right this 0 to 8 it is having an absorptivity of 0.2 and from 8 to 10 let me see that I will be able to answer that now yeah 0 to 6 6 to 8 sorry the figure is not clear sorry about that 0 to 6 it is constant 6 to 8 it is increasing and 8 to infinity it is going constant so now irradiation is also having a distribution like that okay so that is 0 to 2.02 irradiation is 0 to 0.2 this is 0 to 2 and 2 to 5 it is 500 and 5 to 12 it is 500 again and 12 to 16 it is decreasing so this is irradiation so we will come back to that when we are solving so this is irradiation distribution is given and absorptivity distribution is given so taking that the question asked is find the spectral distribution of reflectivity and total hemispherical absorptivity and nature of the surface temperature range so if I this is my surface and surface temperature is having 500 Kelvin and emissivity is total hemispherical emissivity is given to be 0.8 and emissive power is emissive emissivity into eb and irradiation is alpha into g so alpha plus tau plus rho equal to 1 transmissivity of this surface is 0 so I get rho equal to 1 minus alpha so now rho equal to 1 minus rho lambda equal to 1 minus alpha lambda I have been given alpha lambda so at every wavelength if I deduct 1 minus alpha lambda I should be getting rho lambda that is what I have done here and I get rho lambda I get rho lambda using this distribution now what is the next that gives me spectral distribution of reflectivity is that okay now next is I have alpha lambda and g lambda given already now what is that I need to do total hemispherical absorptivity have I defined that yes I have defined that total hemispherical absorptivity is given by alpha lambda g lambda d lambda upon g lambda d lambda both integrated between 0 to infinity this is like the way we define total hemispherical emissivity similarly we solved a problem based on which we took different emissivities in different bands similarly we are taking different absorptivities in different bands so if I do that integration see here in this range both absorptivity and irradiation are constant that is 0.2 into g lambda d lambda between 2 to 6 2 to 6 during that time my g lambda is constant and then g lambda is constant at 500 between 6 to 8 but between 6 to 8 my alpha lambda is increasing okay and plus absorptivity is 1 for 8 to 16 that is where between 8 to 16 what do I have 8 to 12 it is constant and then from 12 to 16 it is decreasing that is what is accounted here so it is basically area under the curves so that integration I am doing if I do that integration I get total hemispherical absorptivity as 0.76 you please sit down over t break t break just do this integration I am just doing simple integration by taking area under the curves now what is the net heat transfer net heat transfer is alpha g you see alpha g minus e epsilon e b so if I do that alpha g minus epsilon sigma epsilon t to the power of 4 alpha we got 0.76 and g is how did I get g as 5000 how did I get g as 5000 the integration of g that is the area under this curve is 5000 so that 5000 if I substitute and 0.8 is the emissivity which has been given sigma and this is t what is this t surface temperature 500 to the power of 4 3800 minus 2835 I get 965 watts per meter square what does this mean it is coming out positive that means it is receiving more than a bit that means the temperature of my body should be increasing with time so the net heat flux to the surface is greater than 0 so therefore the surface temperature will increase with time I think there is another problem with the cover glass I am not going to do that here this is about transmissivity this problem was cooked to explain absorptivity and this problem is cooked to explain transmissivity so I would request you to solve this problem yourself and I will I will take may be one or two questions one question I will take before I sign off so yesterday we could not go to VJT I Mumbai so I am going to VJT I Mumbai please restrict your questions to today's topic or yesterday's radiation topic what was taught over to VJT I Mumbai for questions hello sir my question is if I am getting the radiation if I am getting the radiation from the sun it is long wavelength or short wavelength radiation and second question is if I am using the window for the home purpose I have the double glazed glass and one I have the single glazed glass okay so the whatever the radiation coming inside through the solar is high or low and it is which type of wavelength it is from the solar radiation I am getting whatever the radiation is short wavelength or long wavelength see if you see the question the question can be answered through Planck's distribution so let us see if we take two it is I think it is in radiation that means it should be there in this itself I am in radiation to itself so let us go to Planck's distribution so in fact okay so if I see the Planck's radiation so if you see the Planck's radiation what is solar radiation 5800 Kelvin 5800 Kelvin means if you see here the radiation where is it visible light region is between around 0.5 to 1 micrometer okay I do not know what you mean by short or wave large wavelength yes if I have to answer that way okay the solar radiation that way for any temperature short wavelength will have a higher emissive power compared to large wavelength so is in case of solar radiation the most of the energy is concentrated between 0.08 micrometer to maybe 1 to 5 micrometer okay so but then we cannot generalize like that but generally this is the wave length band which the solar radiation is occurring second question you had the second question was there is a double flare glass and a single flare glass how does the how do they work I have to look at the transmissivity patterns until I see the transmissivity patterns I will not be able to comment what I would request you is to look for the transmissivity distribution of the single flare glass and the double flare that is the answer for your question one more question sir you have just now given an example of aluminum foil that is wound on chapathis or pipes carrying hot fluids which are insulated can you just elaborate how these aluminum foils are going to reflect coldness and aren't they going to reflect the heat also that yeah they are going to reflect both cold and heat both cold and heat see in the first example of chapathi I do not want to lose the heat in the second example when I am doing when I am putting this aluminum foil may be on a hot water pipe which is let us say we have a hot water pipe and there is a flow taking place of the hot water in this pipe here I do not want to lose the heatness from my hotness of from my hot water here again aluminum foil avoids the coldness which is coming from the for cryogenic fluids also you use aluminum foil so it is no matter whether it is for heating application or cooling of cooling application for all reflective for avoiding reflection we do put aluminum foils is that okay I think I think we will move on we will move on professor Arun will take over and start off with Kirchhoff's law.


The function of a closed-loop system is to monitor and automatically maintain a variable at a desired set point in a manufacturing process. Using an example of a heat exchanger, the operation of a closed-loop system is compared with a block diagram. The heat exchanger supplies heated water to a food-processing operation. Cold water enters the bottom of the vessel where the water temperature rises as it passes through steam-heated coils before flowing out of the pump at the top. Each block represents a function of the operation. Lines connecting the blocks indicate input and output signals of each function with directional arrows indicating the process flow. The controlled variable is the actual variable maintained in the process. In this example, the controlled variable is the temperature of the water leaving the tank. Measured variable monitors the status of the controlled variable. Water temperature is the measured variable in the process. The measurement device senses the measured variable and produces an output signal that represents the status of the controlled variable. The thermal sensor that measures the water temperature in the heat exchanger is the measurement device. The sensor provides an electrical signal to the controller and is defined as the feedback signal in the block diagram. Set point is the predetermined value of the desired condition of the control variable. In the heat exchanger, the set point is the programmed value of the water temperature leaving the tank. Error detector compares the set point to the feedback signal and produces an output proportional to the difference between them. Error signal is the output of the error detector. If the feedback signal and set point are equal, the error signal is zero. The controller is the brain of the system. It receives an error signal as it inputs and provides an output signal to the final control element or actuator in this example. A signal from the controller causes the controlled variable to match the set point using the actuator of the system. The flow valve represents the actuator where steam flow is controlled. The amount of energy or steam in this example altered by the actuator is the manipulated variable. Manufacturing process is the operation of the heat exchanger to control the physical variable. Disturbance is defined as a change in the manufacturing process resulting in a change in the control variable. Disturbances occur when the water temperature suddenly changes or stops flowing. Closed loop control and the associated terminology are common within manufacturing systems where precise control is required.