Good afternoon everyone. My name is Athin. I work in Red Hat as a senior software engineer. We work in a product called Gluster which is an open source scalable file system distributed file system which can serve up to petabytes of data. So, before I proceed further I just wanted to know how many of you are aware of Gluster. How interesting quite a few? Okay. So, my topic is about a distributed system or a distributed file system and how we can scale a distributed system. So, going forward this will be the agenda what I will plan to cover. Few terminologies what we need to understand those of you who are involved in distributed system probably they know about few terminologies like what is consensus and what is cap theorem. Then the major thing which comes in designing a distributed system is what are the different challenges what we face in designing a distributed system. So, I will be talking few of them over here and what are the design approaches what we can go with. Then I will cover little bit on algorithm called raft and how this algorithm can be used in technologies which use consistent distributed store like at CD console zookeeper and so many things and then I will be happy to take your questions. So, consensus is a very key aspect in a distributed system. So, as I mentioned consensus is an agreement, but what we need to understand is this agreement is for what and between whom. The answer is pretty simple the answer to what is the operation or the transaction which is coming to my distributed system as a request whether I can perform that operation or whether I can commit that operation that is the decision what I have to make out of a particular distributed system and between whom is the nodes which actually form your cluster in the distributed system whether they agree to go on and commit the transaction. So, these are the two things which we need to be careful about coming to a conclusion about whether my distributed system is in consensus or not. So, ideally another term which comes in our mind when we talk about distributed system is quorum that is normally the quorum what we have here is n by 2 plus 1 where n is the number of nodes. So, consider a cluster which has 5 nodes then if 3 of the nodes are up in my cluster then I can say that I can go ahead and you know my cluster will still be operatable in when if you know there are couple of nodes down. Moving to cap theorem this particular theorem actually tells you that if you meet any two of the following three categories or following three properties that is consistency, availability and partition tolerance then you would actually you know make a distributed system achieve the cap theorem where you can guarantee that your distributed system can work at max potential. So, consistency is where you can say that all the nodes can see the data at a given point of time and that data should be same across all the nodes and availability is that is a guarantee which you know where your distributed store or a node which can have like whenever it sends a request to the other nodes over the cluster it can say that I can get a reply or I can get a response back from the other node or for that particular request. And the third point is really crucial like given your nodes are in a network and if there is a you know network breakage or your cluster goes into a kind of partition and a very few subset of nodes in your cluster are currently operating and the rest of the nodes are broken from the cluster the moment the network comes back you would need to provide a mechanism such that all the nodes which went down and came back are in sync with the operations what went ahead. So, that is the thing which we need to be careful when you said my system is a partition tolerant system ok. So, in any system it has its own set of meta-ata. So, when I say when I consider cluster my meta-ata is all my configuration changes all my state changes what happens in my distributed system. So, there are two different ways of you know thinking about designing this one is with no meta-ata at all and one is with the meta-ata server itself. Now the question what we need to ask us is which option is better should we go with no meta-ata at all and or should we go with a meta-ata server. So, how many of you are actually involved in a distributed system here and how many do you think that we should have a meta-ata server and how many do you think we should not have a meta-ata server also 50-50 looks like. So, I will sorry yeah. So, I will try to cover both of them. So, this is what my experience is about using no meta-ata server currently the product what we have we do not have any meta-ata server dedicated meta-ata server, but these are the challenges what we are currently you know facing while we while you know going towards the scalability. First of all is n cross n you know exchange of network message. So, given a five node cluster and you if you if you say I do not have a meta-ata server dedicated meta-ata servers to store my configuration details what you need to do is every node in the cluster has to have the exact set of configuration information which the other nodes have which requires n cross n machine network or machine way of communicating to each other. Now when this n is pretty small say probably less than 100 you can still achieve it, but think about a case when you want to scale this particular system to 1000 nodes or probably in the you know 10000 nodes can you can you you know can you do this can you can you really you know go in a machine network way of you know exchanging the information. We have seen cases where if I go up to more than 1000 more than 100 nodes it really takes lot of challenges to exchange the information and keep the information in sync across all the nodes. The initialization time can be also pretty high because when when you when you bring up a node. So, what it has to do is it has to get all the nodes from the other sorry get all the information from the other nodes and have them stored in its local configuration which requires a n cross and handshaking. So, if the n goes up it is actually the time goes exponential. So, consider a 1000 nodes you know forming a cluster the initialization time would be really really you know very high. So, which we cannot afford to do in a you know real time distributed system and another key aspect here is a typical split bend situation where you could end up in a situation where you see that one node having a configuration data and the other node also have a similar configuration data, but somewhere different and you do not know whom to believe and whom not to because the way we we sync our data is based on the versioning. So, there could be cases where the version numbers would be same, but you would have different set of data. So, then you you you do not know how to how to solve that split bend situation if you go with this n cross and handshaking way and another key aspect what we see or another key challenge what we see in a distributed system is how do you roll back your transaction when when there is something you know something failing in one of the node or how do how do you know get back to the previous state where where you initiated the transaction. So, these are the things what are normally you know a designer faces if if he or she has to choose the no beta no metadata server way of designing the system and with MDS it if you choose to have a single MDS definitely it is a single point of failure, but that is not the ideal problem because we can still go ahead with you know HAPS probably in the form of replica 2 or replica 3, but it could incur additional network hub because probably the clients what what talk to the server it it does not know whom to send that request it can send to request to any particular node and that node has to each for each and every request that node has to talk to a dedicated MDS server fetch the information and then process. So, it definitely incurs a additional network hub. So, so from a personal point of view I think this is also not something which you would you should go for while thinking about you know solving scalability in a distributed file system. So, the answer to all these problems actually you know starts from here sorry. So, this is an algorithm which most of the you know recent technologies use these days. So, it it is called raft it is a consensus algorithm that I will not be you know going into much detail about raft algorithm because my major focus on of this particular topic is to make you aware that how we can utilize this algorithm and the other technologies such that we can actually you know come up with a good scalable distributed system. So, these are the key functions what raft algorithm offers to you it is an asymmetric that is leader based algorithm. So, in a in a given set of cluster one particular node will be always acting as leader it will it will take the request from the client and it will it will you know then instruct the followers in the in the given cluster to take the necessary action and this algorithm has the intelligence of choosing a particular leader at the given point of time then you know proceed ahead with the normal operation normal operation is nothing, but what exactly a follower does when it receives a request from the leader it is based on a log based replication model. So, whenever you issue a RPC from the leader it actually records that particular transaction in the log which is a replicate mission and then you know that is moved to to the operation you know engine such that it can perform that operation excuse me. So, another aspect of raft algorithm is it actually provides you the mechanism of safety and consistency after the leader changes like in a in a in a particular case when a node is a leader and at that point of time something went wrong and the that particular node goes down you need to you know go forward and select a new leader and such that your data is still safe and consistent enough such that I can go ahead and you know operate or continue to operate on the cluster. And neutralizing old leaders means the moment this this leader comes back again right that the node which went down and again it it comes back it should not be acting as a leader forward because it it went down and during during that time raft actually chose a different leader. So, the moment this guy comes up it should not be acting as a leader because raft does not say that you can have multiple leader at a given point of time. Then client interaction is also a key aspect like client should be able to know that whether a transaction is being committed or not it should not be the case that client. So, so there is a there is a case if if the client sends a request to the raft engine and somehow it it it does not get back a response at a given point of time and if if the client sends another retry RPC request back my raft engine should be aware of that it is a redundant request. So, which and it should understand that client has not got back a response for the earlier request and it has to notify the client that I I have to you know I have to take you know some form of intelligence such that I reply back to the client saying this is what you you are supposed to or you are expecting for. And raft also has a way of doing all the configuration changes like how how we can set up your cluster initially how how we can set up a leader and all. So, I as I said I would I will not be going much detail about all these things probably very few of them how how we especially on the leader election part how exactly we do that. Another important term here is raft actually uses a terminology called term to indicate its own set of time. So, it is a kind of time interval what raft defines and this is divided into two different parts in one T 1 in the first T 1 seconds it goes for an election where it has to elect for a leader and the the the rest time slot it will be actually focusing on the normal operation that is the you know RPC processing. Few of the characteristics what you need to understand is there would be at most one leader per term. So, it should not be like you know in a given point of time your term can have two different leaders. There could be a case where you can lead to a failed election like the followers did not vote for a vote for a particular leader or probably the quorum was not met you probably had you know you probably got back respond equal number of responses from two different set of followers which means that you cannot choose yourself to make your choose yourself to become a leader. So, what you need to do in that case is you need to just drop that particular term and increase increment your term number and move forward for the next election. This point right each server maintains current term value this is the kind of data which is persisted in the disk. This term value is pretty crucial when a leader goes down and comes back and such that you know you should not get into a state where you are actually having the stale information. So, consider a case where you know one leader actually trying to say that I am the leader I can actually you know play a leadership role now in the cluster, but it had old term value compared to the other ones. So, in that case when RAF sees that the RPC requires what it sends along with its term number it is quite old it will reject that particular leader to be or the particular node to become as a leader. So, this is very crucial aspect of RAF and that is what I have mentioned that identifying the obsolete information is pretty crucial in terms of achieving the consistency and safety in RAF. So, these are the server states which RAF maintains as you see from the diagram we have follower, candidate and leader I have already discussed about leader and follower the candidate is a kind of interim state where when follower sees that there is no there is no leader available at this point of time it actually choose to move to a candidate state such that it can vote itself as a leader and then participate in the leader election. And this is exactly how the you know kind of 1000 feet overview of the way RAF works. So, as you see in the first point client actually sends a request to the server consensus module and then this particular server consensus module actually sends another set of RPC request to across all the nodes where this will be logged in its own log replicated machine and the moment it is logged into the log replicated machine it will go to the state machine in the leader and the moment the leader actually commits that transaction it sends back a reply back to the client. The thing which you need to remember here is it is a sequential consistent which means the order at which the request arrived there is a guarantee which RAF provides that at the same order the transactions will be committed. So, these are the different set of RPCs which RAF uses one is request vote RPCs which is purely used for leader election. Then append entries RPCs with no message actually holds the actual data which has to be communicated to the follower for the normal operation and there is another set of append entries RPC which has no message which is used for heartbeat such that you know leader can actually send a heartbeat message to all the followers making them aware that I am alive. So, you need not to go for another set of election the moment the follower misses out any heartbeat at a given particular time interval then it says that I have not got any message from the leader. So, I should actually go to the candidate state and you know starts a leader election. So, this is exactly how the leader election works the moment as I mentioned that you know the heartbeat time is elapsed or the timeout is elapsed the current term which is persisted in the desk is implemented then the state moves forward from follower to candidate it votes for itself and then send request vote RPCs to all other servers and retry until either it receives votes from the majority server that is you know to achieve the quorum and receive RPC or receive RPC from valid leader or it can actually have a election timeout and then you know the which is a failed vote or a kind of election timeout set such that it can actually increment the term and you know move forward for the next set of election. So, the another you know thing which we need to you know notice here is there are two different properties which raft guarantees out of election which is safety and liveness. Safety is actually you should have at most one winner at a given point of time as I mentioned in my previous slide you cannot end up having a situation where at a given point of time your algorithm would choose two different leaders and liveness is some candidate must eventually win to you know become a leader. This is achieved with a with a you know with a way that your election timeout is not static it actually varies from few you know microseconds between different nodes. So, if your election timeout is static you could end up in a situation where all candidates are receiving a vote or receiving a request from one particular follower. So, it will immediately you know reply back that ok my job is done you can actually choose yourself as a leader. So, it will be always like one particular node is playing acting as a leader instead of you are switching between different nodes in the cluster as a leader. So, yeah that was you know very basic about how raft works. Now, moving to consistent distributed stores. So, before I talk little bit on the consistent distributed store I would like to tell you that in a given distributed system or a distributed file system there are three key aspects what you need to focus on one is how to store your configuration data like the like any state changes whatever is going through in your node you need to store that data how would you need to sync your configuration and how would you need to perform your transaction. So, these are the three things what you need to focus on while designing a distributed system. Now, this consistent distributed store is something where you can actually have a store distributed across your cluster it should not be local and you can actually store those configuration data using this consistent distributed store. So, it actually uses a key value pair for ease of use and believe me there are several such consistent distributed store available with the latest technologies now. Yeah. So, I have actually explored HCD and console and little bit on the zookeeper as well. So, the current product what we use it is in it is written in C and our community is more comfortable in C. So, we chose not to you know explore zookeeper this is this particular you know thing is still in a kind of POC mode we haven't implemented our distributed system using HCD as of now, but in the near future we are actually planning in the next release we are planning to do that. So, as the name says HCD is a distributed kind of HCD it is a core OS open source project it is actually based on draft. So, that is why I chose to cover few of my slides about draft it is very highly available and reliable sequentially consistent as the as draft guarantee is that the order at which your request will come in the same order the operations or the transactions will be committed and watchable. This is this is really a you know crucial requirement what we have while designing our system because we would need to have a kind of a method or mechanism such that I can you know constantly pull on a particular key for a given namespace I and I want to see whether anything is getting changed for that particular key. So, it HCD actually provides this facility it is exposed via HTTP it can be runtime configurable which is a kind of selling feature I heard that you know zookeeper was not doing that I am not sure whether it does that at this point of time it is durable as well like you can actually you know take backup or snapshot and then probably restore is and you can actually you know set up your keys in a way that it can actually stays there for some certain amount of time and then probably it can expire which is also kind of very cool feature to work with. Why I choose to you know go for HCD it has a real vibrant community if you look at their GitHub page there are around 500 plus application like kubernetes cloud foundry they are using HCD there are around 150 plus developers and they are actually following some stable releases I heard about something HCD 2.0 which was released so this is the slide where I will be spending little bit more time. So, whatever we learnt at this point of time is theory now if you visualize all this raft and HCD what we would need to do is given a n number of nodes in a given cluster what you have to do is you have to set a sub cluster in your in your big cluster using HCD. So, given say you have 1000 nodes or say 100 nodes you can set up a cluster of 5 nodes which uses HCD and use that particular cluster to store your configuration which means if any request comes into any of your node you have a cluster which can guarantee that whatever configuration you would need to store that is that is reliable that is consistent. So, you would not need to you know send 1000 odd RPC request to all the nodes in the cluster to store its own set of configuration. So, you would reduce the number of RPC request by any means and whatever you know features HCD provides to you that is also guaranteed if you are using HCD or any form of distributed consistent store in your application and yeah. So, as I said no burden on application to maintain the consistency. So, we have been facing lot of challenges to maintain the consistency of the data while syncing or storing across different nodes which you would not need to you know bother about because that has been already taken care by HCD and it is a proven thing. So, only thing what you need to focus as you just write or you just plug in HCD in your application form a set of cluster. So, the way you can do is the moment you bring up first node it should have HCD running on it the moment you bring up your second node it should also bring up HCD in it. So, in this way the probably if you choose to go with 5 number of nodes in your HCD cluster the moment you reach 5 nodes the further onwards you do not need to you know launch HCD they will be acting as normal set up, but the initial 5 nodes will have all the HCD intelligence in it and it will be playing a key role in storing all the configuration data. And I think that is the main motive of how we can make our system a scalable and these are the references what I have put forward here which you can go through later on. There is a very good visualization web unit which the first one which I have pasted here that actually explain how exactly the raft algorithm works and now I am open to take questions. So, you said you explored console as well right. So, what was your thought process to choose HCD over the console as it provide a health checks as well as console provides health checks on top of the whole infrastructure. So, if you have to integrate any third party application in your project you would need to look forward and see how the community is working at this point of time whether they are coming with you know proper stable releases or not because that is also very crucial role. So, I did have a slide where I spoke about HCD has around 500 plus applications which they uses HCD. So, that was one of the major point what we why we went for HCD over console because honestly speaking we do not see any much of difference in terms of the actual underlying architecture or actual existence guarantee what HCD zookeeper or console provides. But, it is the ease of use or it is the guarantee what the community provides that is what you need to you know look for. So, the main reason of going for HCD was this community itself and kind of usage what is been happening. So, any drawbacks that you saw while when comparing the other. So, what was the main reason like you said ok zookeeper was not the right choice for your. Because, our project is not in Java and our community also does not like to use Java and zookeeper zookeeper actually uses an algorithm called PAXS which was actually the base from where the raft was originated from. PAXS was pretty difficult to understand and if you look at the raft algorithm the way it was implemented inside the HCD it is a 700 odd lines of code in go. So, that was one of the reason why we did not actually you know want to go with PAXS. So, does it mean that you guys are moving from the no metadata store to a metadata store by using HCD? It is a kind of metadata store, but at the same point of time as I say it is not a dedicated metadata server that the node itself will have its own set of compute engine as well. So, it will work like a class node participating in the cluster, but it will have its own set of HCD knowledge as well just to store additional configuration details. So, in that case if let us suppose you are talking about a 100 node cluster, does it mean that HCD will be running on a 100 node cluster? No, no, so it is 100 nodes. So, if you so normally right if you look at the HCD or console documentation they prefer that you should set up 3 to 5 nodes in the cluster just to achieve the high availability. So, our plan is to have 5 nodes with HCD running and the rest of the nodes will be only running the you know cluster daemon. So, you are going with the elastic search concept where the master nodes and the data nodes. So, other question is more about that like there is a safe storage file system as well and that is also from the Red Hat now. So, like I would like to understand the methodology like why safe and G-Luster FS both exist as of now. If you can explain like the thought process. So, that is actually honestly that is of the topic, but it actually depends on the kind of workload what you are looking for. Cluster is really a file system which works over the file well compared to the safe, but if you look at the workload where you need block and object interfaces, safe does better than G-Luster at this point of time. So, if you look at the open stack area right safe is really playing a very you know good job over there, but if you talk about backup or archival kind of workloads then G-Luster is definitely a choice over safe. So, we actually you know product is these two things and we call them as a Red Hat storage and customer is free to choose that product depending on their workload. So, we do not tell the customer that you should go for G-Luster or you should go for safe. It depends on the kind of workload what you have and based on that we actually suggest what product you can go with. I am not able to hear your thoughts on a multi-master metadata server kind of model. Why do you think that or other what advantages you will get if you have a multi-master? They could replicate the state information and the other metadata information among themselves. So, they leverage ETCD and on the network I can use DRBD with that. So, even in a single master right even if the rest of the nodes are followers you would still replicate all the informations in the other cluster. It is that the concept only says that your client will only talk to a particular node which is a master and then master will actually eventually send the request to all the followers to sync all those configuration data across all the nodes. So, at the end of the day all the nodes are actually the one which are crucial or which are playing a role of master for the overall cluster. So, if you visualize that your cluster is 100 nodes and where the only 5 set of nodes are forming an ETCD cluster. Even if there is one node which is currently playing as a leader or master, but from the outside from the 1000 feet overview what I can see is those 5 nodes are actually mastered to me because without the information I cannot operate on that cluster. So, for me kind of requirement what I have I can actually satisfy my requirement even if I go with a single master. Exactly, because your client would not come to know where to send the request and where not to and as I said if raft actually guarantees that there is only one leader at a given particular point of term and having different masters would definitely lead to a different issue until and unless you change the underlying algorithm, yeah absolutely, absolutely. No, so it is actually for the complete cluster, but all the nodes in the cluster would be aware of who is actually running with HCD. So, if there are 5 nodes running with HCD the rest of the nodes have that knowledge that these are the 5 nodes which are running with HCD. So, if any given point of time I have to fetch the configuration data I have to talk any of this particular node in the cluster which raft already provides that implementation that this is that my leader at that given point of time. We are talking about 100 terabytes of data. So, if there is a one master it means a leader and every rights and rights goes to that leader there will be a problem right. No, when you talk about data are you talking about the application data or the metadata? I am talking about the application data with the metadata because if the there is a huge data sets. So, obviously metadata is also beginning to be used in terms of freedom and right. It means I am hoping that ok reads rights will go through the leaders not directly to the storage nodes. Okay, this particular thing is actually for managing the cluster. So, the way our cluster works is for the file operations right we would not need to talk to any particular leader or particular follower in that case. So, the clients which connect or the mount point if you have a mount where you are running cluster client it has the intelligence. Okay, it is a smart client that which is the metadata. Yes, yes, because we have a algorithm called DHT that actually is aware of what all bricks or the data storage units you have. So, you do not need to know where I have to forward my request because your client is intelligent enough to you know guarantee that. How frequently client will pull the data from the nodes from the HCD cluster? I did not get your question correctly. So, you said client has a metadata information from the metadata servers because that is how it knows that this bricks resides on this. So, this client is actually the one which I am talking is the CLI client where you can issue the cluster command. Got it, but still like let us suppose this bricks is where this particular brick is deployed and this particular data nodes. So, client has to know this is the data node that I have to talk and write the data. That is the file operation client. The one which I spoke about is the CLI client, the command line interface client which talks to cluster D. So, if you can explain the read and write operations what would be the flow if somebody writes from the client to storage cluster and reads the whole operations how it will happen it will be great. So, our management operation and file operations are separated all together. So, management operations do not interfere with the file operation. So, if you talk about the actual read and write what happens is your client is sitting here whereas you have a server stack as well. So, in the client it has the intelligence that whenever a request comes in for a write or read it must be having a file name or I node number or whatever form it is. So, it performs an operation that is distributed hashing and it can come to know to which particular data storage unit it has to send the RPC request. So, there I do not need a CD cluster. So, it means that you are saying the consistent hashing happens when you start writing into a file. So, does it mean that the client uses the consistent hashing to get the node information. Yes. Any more questions? Yeah. Hello, can you hear me? Yeah. Yeah. Can you speak up little bit? Yeah. Is it ok now? Yeah. Yeah. Actually, we are using Docker containers and we have our nodes in these containers and we are using HAProxy and which has its own round robin algorithm right. So, now can we use ETCD on these container nodes on the application container nodes in order to you know for a configuration information metadata information along with Docker and the HAProxy. So, how would it work? You can use it right because so if you can actually make your containers running with the HCD which you can definitely do in my opinion. So, in that case what you are having here is if you can form a cluster with all these Docker containers and run the HCD in all those Docker containers, you can still use the leverage of a distributed consistent store in the form of HCD and store the data in any of those Docker containers. Say for example, you are running 10 containers out of a where you want to set up a HCD cluster of three particular Docker containers, but you definitely need some tweaking in your containers itself such that your containers can understand that who is who which node is part of the HCD cluster and who are not. Yeah. But we need some tweaking right. Yeah. You need to do that. Hi. Any more questions? Yeah. So, I want to ask you one thing here is like we are going, we are going with the configuration management system. So, what I'm asking you is we are going with an approach of configuration management where we maintain our configurations. Okay. So, we are putting like infrastructure as a code, but again when we talk about ETCD it has to provide the configuration to the whole cluster. Right. So, if I have a configuration management software then will it be possible? It will be a conflict right? As per my opinion right, ETCD is not meant for configuration management. There are several other tools which you can explore to you know have for configuration management probably different orchestration tools like Chef, Puppet. Correct. So, what I'm saying is you know in a configuration management software if you run a client then you get all the configurations to the host. With the ETCD approach you have your local configurations and then you fetch it from the local cluster no need to contact to a master somewhere outside the cluster. Okay. So, now the approach is if I have a configuration management software I can't have you know five machines dedicated for you know a configuration management store. You don't need to do that. So my my requirement was I don't want to set up ETCD over all the nodes in my cluster. But if you need that I don't want that kind of segregation you can still go ahead and you know choose to have ETCD running in all of your nodes because ETCD doesn't you know restrict you to do that. You can still go ahead. So, ETCD will provide that guarantee that you would need to you know send your request to one particular node to get back that configuration data. So you could yes, yes, yes, yes. If you really want to use ETCD as a store data store so you can always write the API is hook into your shape or puppet thing and then face the data. So, data bags for example in a shape you have a data bags. So, data bags are nothing but a JSON store right. So, you can always put the data as a key value into your ETCD but obviously you have to write a wrapper to face the data from there. So, that you have to do. There is no out of the box solution here. Yes, yes. Okay. Thank you. Thank you.


The EGOV.CM program led by the National Agency for ICT, ANTIC, aims to improve access to government information and services, provide IT support to the public administration reform program, and create an appropriate legal and regulatory environment. However, this can be difficult due to the emergence of cybercrime globally, which requires changes to outdated legislation written prior to the digital era. This has resulted in impunity as criminals are able to operate freely within the country, while e-government transactions may not be protected, leading to citizens being discouraged from using these services. The ELOS of 2010, Cybersecurity and Electronic Communications have been created to protect ICT networks and critical infrastructure, providing an enabling environment for e-government services. These research notes highlight the importance of the ELOS for effective Cameroon public administration and discuss the challenges for their successful implementation. This article was authored by Patricia Ngyemeneng Asongwi.


Oh. Hi there. This is rude, I'm sorry. You caught me in between doing some voiceover stuff. When I get a dry mouth, this actually helps quite a bit. So, anyway, I'm glad you're here because I want to talk to you about something. I have an idea for patrons of Margarhous, and I've talked to a couple of authors who I am now currently voicing the audiobooks for, and they like the idea. What do you think of the idea of me releasing chapters of the audiobooks that I am narrating as I finish them before the book is ever available online anywhere else? You would hear each chapter of the book as I finish it. I mean, within minutes of me finishing the audio, you would hear it. Now, we'd only be able to do this for a while because once I finish the book, then it would go on sale, so that we'd have to remove those from the patron-only area of Patreon.com, but up until that point, you'd be able to hear it all. So, curious if and whether or not you think this is a good idea, if there's something that you would like to do. If you're a patron, this is definitely that I am definitely talking to you. If you're not a patron, this only applies if you become a patron later on, but I'm definitely, sorry, Apple, I'm definitely looking for your opinions on this. So, let me know in the comments below what you think of this idea, and if you like it, we'll go ahead and move forward with it. I think it'd be a lot of fun and it gives you an opportunity if you're a fan of audiobooks, it'll give you an opportunity to essentially hear an audiobook for free, aside from what you're paying as a patron, but that's for the Weird Darkness content, Daily Dose of Weird News and everything else. This is more of like a bonus for patrons. So, let me know what you think. Comment below. If you like this idea, give this video a thumbs up. If you don't like this idea, give it a thumbs down. That's perfectly fine. I really do want to know what you think of this, all right? So, New Weird Darkness coming up here later on tonight. I'm working on it right now. Just had to take a break and get my mouth wet again. See you later, Weird Ocean.


Helium is to be compressed from 120 kilopascals in 310 kelvin to 700 kilopascals in 430 kelvin. A heat loss of 20 kilojoules per kilogram occurs during the compression process. Neglecting kinetic energy changes determine the power input required for a mass flow rate of 90 kilograms per minute. Parsing that out, we recognize that our steady flow device here is a compressor, as evidence from the name, as well as the description of the process. Furthermore, we know that our working fluid is going to be helium. We don't have tables for helium, which means that we're going to have to treat helium as an ideal gas and assume constant specific heats. We are told an inlet temperature and pressure, as well as an outlet temperature and pressure. We're given a specific rate of heat rejection, so a little cue out. We are told a mass flow rate in kilograms per minute. Furthermore, we recognize that because this is a steady flow device with one inlet and one outlet, the mass flow rate entering has to equal the mass flow rate exiting, which means 90 kilograms per minute describes both the mass flow rate in and the mass flow rate out. Jumping into our steady flow device's table, we can see that for a compressor, the goal of the device is to increase the enthalpy of the fluid. That primarily occurs in the form of pressure, but the goal is to increase enthalpy. The source of energy for that increase in enthalpy is work input. So we are putting in work to get out a change in enthalpy. As a result of that, we would expect to see a work input, which is implied here as the thing that we're looking for, and a change in enthalpy from state 1 to state 2. I will start with a rough diagram, and for a compressor, we typically draw a shape with a converging cross-sectional area, and then an inlet and an outlet on the big and small sides. Typically, that is drawn as though the fluid is going from left to right, but that doesn't really matter. On this diagram, I can indicate that there will be a work input. I'm drawing that as a specific work. It doesn't really matter. I could draw that as a power input as well. I'm going to describe my inlet state point as state 1, and my outlet state point as state 2. I will indicate that my control volume here includes an inlet, state 1, and an outlet, state 2, as well as a work input in the form of shaft work and a heat rejection in the form of a specific hue out. Furthermore, while I'm here, I could indicate that helium is the working fluid, and I could parse my given information into an inlet and outlet set of state point properties. At state 1, we have a temperature of 310 Kelvin and 120 kilopascals, and for state 2, I have a temperature of 430 Kelvin and a pressure of 700 kilopascals, and I will add into that my mass flow rate at both state points, 90 kilograms per minute, and that my specific hue out is 20 kilojoules per kilogram. I'm looking for a power input, which implies that I'm going to be using an energy balance to relate how the enthalpy increase corresponds to the power input. To do that, I will write out my energy balance. My energy balance is on the control volume, and that control volume is an open system, so I'm going to have to account for energy crossing the boundary as heat and or work and or the energy associated with a moving mass. I'm also going to be treating this as being steady state, which means I'm neglecting the effects of time. So the compressor is assumed to be fully warmed up and is running steadily, so regardless of when you look at it, the temperature of the inlet and the outlet don't change. I will add to my list of assumptions that I'm treating it as an open system, even though I don't necessarily have to. And then I could think through what terms are going to be appearing in the energy balance. Since I'm using steady state analysis, I'm likely going to be using the rate form of the energy balance, which means that I'm probably going to end up with a rate of heat transfer, a rate of work, and then a change in energy of the fluid itself, which can include enthalpy and kinetic energy and potential energy. While I'm listing assumptions, it might be beneficial to me to assume that there's no heat transfer in, that is, that the heat transfer that's occurring is only in the outward direction, and that there is no work output, that is, that the only work occurring is in the inward direction. We weren't given enough information to know of any other sources of work or heat transfer, so it's reasonable to assume that none occur. Lastly, I will assume that any changes in kinetic or potential energy are negligibly small. I don't necessarily have to think through all these assumptions right now. If I wanted to, I could start my energy balance and then at each step of the process, eliminate some of the terms, but by thinking through it ahead of time, I can build a plan for my energy balance and think about what it is that I'm actually trying to accomplish with that setup. So back in my energy balance, the change in energy of the control volume is equal to the energy entering minus the energy exiting. I'm going to divide all three terms by dt, at which point I have the rate of change of the energy of the control volume is equal to the rate of energy entering minus the rate of energy exiting. The rate of change of energy of the control volume is zero because of the assumption of steady state, which means e.in is equal to e.out. Since it's an open system, energy can cross the boundary in the form of heat, work, or the energy associated with the moving mass. So I can write out q.in plus work.in plus the sum in of m.theta is equal to q.out plus work.out plus the sum out of m.theta. Next, I can neglect the terms that I've assumed are negligibly small. Since I have a rate of heat rejection, I'm neglecting q.in. That was assumption number three. Since I have a power input, I'm neglecting a power output. That was assumption number four. So I have power input plus the summation of the mass flow rate times the specific energy of the moving mass for all of the inputs, which of course there is only one. It is state one. So I can write that as power input plus m.1 theta one is equal to q.out plus the sum of the mass flow rate times the specific energy of the flowing mass for all of the outlets, which of course there is only one. It is state two. Then I can expand my theta term. Remember that theta could be specific enthalpy. It could be specific kinetic energy, and it could be specific potential energy. Sometimes neglecting changes in kinetic and potential energy, whatever the kinetic energy is at the inlet, it is going to be the same at the outlet. And kE in one and kE in two are going to be the same. It's important to note that I'm not saying that there is no kinetic energy. I'm saying that whatever the kinetic energy is, it isn't changing. Because it appears on both sides of the equation, it disappears. It's not that there is no kinetic energy. It's that there is no change in kinetic energy. Making the substitution I have m.1 times h1 specific kE1 plus specific pE1. Note that I could substitute in there 1 half times velocity squared plus gravity times height. But since I'm going to be cancelling it anyway, there's really no point. We'll move this over to keep my equal signs aligned. And then I will recognize that my mass flow rates are going to be the same. I know that because of the mass balance. To formalize that, I could write out a mass balance. The mass balance begins the same way. I have delta m is equal to m in minus m out. I divide all three terms by dt at which point I have dM dt which is zero because nothing can change with respect to time. Is equal to the sum of all the mass flow rates entering minus the sum of all the mass flow rates exiting. That means m.in has to equal m.out because there's only one inlet. It is state 1. And because there is only one outlet, it is state 2. m.1 and m.2 must be the same. I will abbreviate that as just m. And in fact, I know that quantity. It is 90 kg per minute. So over here I can group together my mass flow rates and factor out the mass flow rate itself. Since what I'm looking for is power input, I will rearrange to solve for power input and then I can neglect changes in kinetic and potential energy as a result of assumption number 5. Therefore, the power input is going to be q.out plus the mass flow rate times the change in enthalpy. So let's think about it. We are increasing the enthalpy, which means that we should have a positive change in this delta here. That represents how much power we have to add. And the presence of heat transfer means that we have to increase how much power we are adding. So losing some of the energy in the process means that we have to add more work in the process to reach the same endpoint. That makes sense. Let's see if we can really set up correctly. In my q.out term I recognize that what I'm actually doing is going to be plugging in mass flow rate times specific q.out which means that at this point I know mass flow rate I know specific q.out the only unknown is delta H. When I evaluate a delta H I have 3 options. Option 1 would be to determine H1 and H2 look them up in tables and subtract those results directly. I could approximate delta H by coming up with a line of best fit for its specific heat capacity and perform that integral. Or option 3 would be to assume that the specific heat capacity doesn't change. That is, whatever it is it is the same across this entire temperature change. Therefore it would come out of the integral. That comes from our definition of Cp which is del H del T. And in fact because this is an ideal gas internal energy and enthalpy are only functions of temperature which means that we only have to use dH dT. Furthermore we don't need this to be a constant pressure or constant volume process because it's an ideal gas when we evaluate delta H what we're using is Cp. If we were evaluating a delta U we would use Cv. H is to P U is to V. Cp is dH dT Cv is du dT Harry Potter ultraviolet In fact I should add helium is ideal to my list of assumptions at which point I can write dH is equal to Cp times dT and integrate both sides. On the left hand side I just have delta H. On the right hand side I have the integral of Cp as a function of temperature dT. If I make one more assumption here that the specific capacity of the helium is constant then that Cp term would come out of the integral and I would be left with Cp times T2 minus T1. So my energy balance is now mass flow rate which I can factor out of the heat transfer term and the change in enthalpy times specific Q out plus Cp of helium times T2 minus T1. While we're here let's talk a little bit about why we're assuming Cp is constant. If we had helium tables the best thing to do in this circumstance would be to look up H1 and H2. That would provide the best answer. However we don't happen to have a set of tables. In the appendices of our textbook the best thing we have are specific heat capacity values. If I jump into table A21 I can see that I have specific heat capacity values for a variety of gases and this is the best data I have for helium. Note this bottom row for monatomic gases includes helium, neon and argon. So we're going to be using Cp over R is equal to 2.5. That's the best thing we can do because it's the only thing that we can do and still evaluate a delta H. Therefore we're making the assumption of constant specific heats. We know that for an ideal gas across a relatively small temperature change this is only a temperature change of around 100 degrees celsius which isn't much for an ideal gas this should provide relatively accurate results. So it's an okay assumption even at that. So my Cp value for helium is going to come from table A21 and that is specifically the molar specific Cp value divided by the molar specific gas constant that's what's implied by this horizontal bar above the value is equal to alpha plus beta times temperature plus gamma times temperature squared plus delta times temperature cubed plus epsilon times temperature to the fourth power where alpha is 2.5 beta is 0 gamma is 0, delta is 0 and epsilon is 0. Therefore the molar specific Cp value divided by the molar specific gas constant is 2.5 Therefore the molar specific value for helium would be 2.5 times the molar gas constant. The molar gas constant or universal gas constant is 8.314 kilojoules per kilomole kelvin you can get that from the inside of our front cover of our textbook. Down here at the bottom we have a couple different values for the universal gas constant we have kilojoules per kilomole kelvin feet pound force per pound mole rankine and BTUs per pound mole rankine kilojoules per kilomole kelvin is going to be the most convenient here because I have a problem in metric units. So if I take 8.314 kilojoules per kilomole kelvin and multiply that by 2.5 I get a result for the molar specific heat capacity of helium for that I will use my calculator and I get 20.785 kilojoules per kilomole kelvin that is all well and good but I recognize that I want to yield a value in kilowatts in my energy balance calculation which means that I eventually need the kilograms in the mass flow rate to cancel so I am going to want kilojoules per kilogram kelvin instead of kilojoules per kilomole kelvin so I want to convert this value from a molar specific specific heat capacity to a mass specific specific heat capacity to do that I will divide by the molar mass so mass specific heat capacity is going to be molar specific heat capacity divided by molar mass which means I am going to take 20.785 and divide by the molar mass for helium for the molar mass for helium I will jump into table A1 which is about the closest thing I have to a periodic table on table A1 I see that the molar mass of helium is 4.003 kilograms per kilomole excuse me kilograms per kilomole at which point I am left with a result in kilojoules per kilogram kelvin so 20.785 divided by 4.003 that yields 5.192 kilojoules per kilogram kelvin and I will note this value came from table A1 just to try to make that clearer for students who aren't following along with the video so I am taking 90 kilograms per minute I am multiplying that by the quantity 20 kilojoules per kilogram plus 5.2 kilojoules per kilogram kelvin times a temperature change from state 2 to state 1 which would be 430 minus 310 for that let me clear up some space much more better and take 90 kilograms per minute and multiply by 20 kilojoules per kilogram times 5.192 5.192 kilojoules per kilogram kelvin multiplied by 430 minus 310 multiplying 5.2 kilojoules per kilogram kelvin by a temperature change in kelvin will yield a result in kilojoules per kilogram multiplying a quantity in kilojoules per kilogram by a quantity in kilograms per minute will yield a result in kilojoules per minute I want kilowatts which would be a kilojoule per second so I am going to divide by 60 out front here that means I will be left with kilojoules per second which is a kilowatt now let me jump back into my calculator and take 90 divided by 60 times the quantity plus 5.19236 times 430 minus 310 which yields 964.625 so it takes just under a megawatt to run this compressor and result in a temperature change of about 120 degrees celsius with a mass flow rate of 90 kilograms per minute that makes sense as 90 kilograms of helium every minute is quite a lot of helium remember that the density of a gas like this is relatively low so that means a lot of volume has to be processed by this compressor also note we didn't actually need the pressure all we actually cared about was a change in enthalpy and for an ideal gas specific internal energy and specific enthalpy are only functions of temperature as a result of that all that really mattered was the temperature we don't even really care about the pressures


Hello students, I am Ganesh B. Agulavi working as an assistant professor in department of mechanical engineering, vulture used of technology, Solapur. In this session we will see theory and design of carburetor per second, learning outcome. At the end of this session students will be able to design the simple carburetor and also will be able to evaluate different parameters of simple carburetor. Now in the previous session we have seen the introduction of simple carburetor. So there we have seen the air is flowing in the downward direction as this is the downward type of the carburetor and the fuel injection is from this tube. So we will consider the section 11 at the inlet, section 22 at the throat and you can consider this as the section CC or 3. This is the throttle valve and this is the difference between the height, the nozzle tip is getting opened over here. So this is considered as a reference line and the petrol level in the float chamber will assume it is to be constant. So this is the jet. Now we will use the different relations and then we will try to get the air fill ratio. For that we required mass of air and mass of air considering compressibility of air. Compressibility of air means there is change in the density. For air applying steady flow energy equation at section 11 and section 22. So for that we can use the relation which we have studied in previous subjects. So try to recall steady flow energy equation. You might have studied in the basic mechanical engineering in the first year. Yes. So did the steady flow energy equation which is also called in the short form ESFEE. So H1 plus C1 square by 2 plus Q is equal to H2 plus C2 square by 2 plus W. So this is the section 11, this is the section 22. So this is your steady flow energy equation. This is the enthalpy at the inlet, this is the velocity of the fluid at inlet and this is the heat supplied which is equal to enthalpy at section 22 that is throat velocity at the throat and this is the work developed by the fluid. Now if we pass the fluid through the pipe, it will pass the fluid through pipe. It will not develop any work done. So for that purpose W can be neglected over here and as I have told you the complete carburetor is insulated one. So there is no heat transfer. So from this equation I can neglect Q and W. Then you just solve for so Q and W will be neglected. Then what is remaining? H1 plus C1 square by 2 which is equal to H2 plus C2 square by 2 ok. Now in this case C1 is to be neglected once again because it is very C1 is having very small quantity that is why usually it is neglected. So what is remaining? C2 square by 2 is equal to H1 minus H2 that is written here. So C2 will be square root of 2 in the Cp in the bracket T1 minus T2 because enthalpy H1 could be replaced by CpT and H2 also CpT2. So what will happen? The H1 minus H2 CpT1 minus CpT2. So Cp is taken common then thus the velocity at throat can be calculated if we know the temperature of the surrounding air inlet air and the throat temperature of the air ok next. Now I can take a T1 common. So equation will become C2 is equal to square root of 2 CpT1 in the bracket 1 minus T2 by T1 ok. Now try to recall the Cp of air if not given where assuming 1.005 ok next equation is square root of 2 CpT1 in the bracket 1 minus now T2 by T1 could be replaced by P2 by P1 because flow through carburetor is once again assumed to be isentropic. In that case we can replace T2 by T1 by P2 by P1 raise to gamma minus 1 by gamma ok there. You just go on reducing it you just go on reducing it then you will be getting the mass of air mass of air relation is equal to P1A2 by R square root of T1 under square root of main square root of 2 Cp in the bracket P2 by P1 raise to 2 by gamma minus P2 by P1 raise to gamma plus 1 by gamma bracket complete. Now this is the theoretical relation whenever any fluid flows through tube pipe then its coefficient of discharge is to be considered because theoretical flow cannot be equal to practical flow practical flow depends upon the material used for that pipe or tube and its friction factor. So, the manufacturer is supplying you this coefficient of discharge that is why the actual mass flow rate of air is the multiplication of Cd into Ma. So, you can calculate this one now. Now for fuel we can apply the Bernoulli's theorem. So, this is the Bernoulli's theorem ok. So, now here we are going to calculate for the fuel. So, the fuel pipe and the you are a float chamber in the float chamber atmospheric pressure section Cc or section 3 3 we assumed and at the throat the pressure is 2 ok. So, here this is the P3 P3 is nothing but Cc pressure and what pressure is acting in the float chamber atmospheric pressure. So, P1 and P3 are same. So, I can replace P3 by P1 also. So, this is P3 by rho f plus C1 square by 2 is equal to P2 by rho f plus C2 square by 2 plus Gz. Now this C2 is nothing but velocity of a fuel injected at the throat ok. Now as C1 is very very small can be neglected then P1 is also equal to P3. So, this equation I can reduce for C2 then we will get velocity of fuel injected at the throat is equal to square root of 2 by rho f in the bracket delta P minus rho f Gz. Now what is the delta P? Delta P is the difference in the pressure that is P1 minus P2 P1 minus P2 for delta P is equal to 0 mass of fuel injection is going to be 0 with decrease in the P2 with decrease in the P2 mass of fuel increases ok just keep in mind that point. So, this is the velocity of fuel injected at the throat from continuity equation we can write. So, this continuity equation recall yes m is equal to rho AC ok. Now so, mass of fuel after substituting in the rho AC here rho f A 2f and C2. So, A f as it is written Z. Now if they do not give in the numerical the value of the Z you can neglect this one. So, remaining parameter will be 2 rho f delta P ok. Now here also take now here what you can do in the previous equations we have derived M A and here M F. So, you can take M A by M F you will be getting the air field ratio. Now we will consider the second case neglecting means the density will remain constant then I can apply the Bernoulli's theorem. So, P1 by rho A plus C C1 square by 2 is equal to P2 by rho A plus C2 square by 2. Now this equation is for air that is why here suffix AA is written neglecting A1 and writing the equation for C2 square root of 2 P2 P1 minus P2 by rho A from the continuity equation I can write M A is equal to A2 square root of 2 rho A delta P. So, here also neglecting the compressibility. Obviously, actually the air is compressible, but if you are interested to find approximate air field ratio then you can adopt neglecting compressibility. Then actual air flow rate as usual is equal to coefficient of discharge into theoretical air field, theoretical mass flow rate of air. So, this is the third equation. So, we will be having the two air field ratios. First air field ratio based on compressibility, second air field ratio neglecting the compressibility ok. So, depending upon your accuracy you can select it. Now you can take once again the air field ratio and you can compare it. It is always recommended to use the accurate or compressibility of the air, accurate method and approximate method. For the accurate method you have to assume the air to be compressible. For more study you can refer IC engine Fundamentals by Hewitt and second book Fundamentals of IC engine by H N Gupta. And from these two books you can solve the numerical cells. Thank you all.


This 10th year of Daily Tech News show is made possible by its listeners. Thanks to all of you, including Ms. Music Teacher, James C. Smith, and Miranda Genel. Coming up on DTNS, Microsoft and Adobe are going in on A.I. imagery, a digital camera community mourns one of its own, and when it comes to flagship devices, what is really the killer spec that we need? This is the Daily Tech News for Tuesday, March 21st, 2023. In Studio Redwood, I'm Sarah Lane. From the suburbs of Atlanta, I'm Terrence Gaines. And I'm the show's producer, Roger Genel. Well Terrence, we're glad to have you with us. I am envious of you being on the other side of the country from me because we're getting a lot of rain here in California, but what's new? Nothing much. I may have to be muting myself because I caught a cold and it's my fault, totally my fault. Never exercise and then go right outside and do lawn yard work. Been there, been there. Well, it is spring, so perhaps sunnier days are on the horizon for everybody. Meanwhile, let's start with the quick heads. TikTok made changes to its community guidelines, expanding its rules on synthetic and manipulated media. The platform now requires all realistic A.I. that's generated content to be clearly disclosed, either with an overlaid sticker or within the description, kind of like ads. The rules also explicitly prohibit synthetic media that contains the likeness of a real private figure or a public figure endorsing a product. Alright, Microsoft subsidiary, Nuance Communications announced a new application to automatically generate drafts of clinical notes for clinicians after a patient's visit called Dragon Ambion E Experience Express. That's a big word. The app uses the GPT-4 model and generates a draft within seconds of a visit rather than Nuance's previous solution, which took about four hours. I think we'll have some happy clinicians in our audience. If that's you, do let us know. We'd love to hear from you. Google flagged several apps from the Chinese e-commerce company Pin Duo Duo as malware, suspending its official app in the Play Store. Google will use its Google Play Protect feature on Android to block users from installing third-party APKs of these flagged apps and also warn users who already have it installed to remove it, or them. You know, there are more than one. Pin Duo Duo's spokesperson denied the speculation and accusation that its app was malicious at all. Alright, Apple analyst Ming-Chi Kuo reports that the upcoming iPhone 15 with a USB-C port will only allow faster charging speeds on Apple-certified cables under its made-for-iPhone program. Currently, the iPhone 14 supports up to 20-watt charging on Lightning with the iPhone 14 Pro supporting 27-watt charging. That makes sense for Apple to have to use a special cable. Yeah, help proprietary of them. NVIDIA announced its new DGX Cloud Service at this year's GPU Technology Conference. The service lets users rent virtual versions of the company's DGX server boxes. Each virtual server will feature 8 NVIDIA H100 or A100 GPUs and 640 GB of memory. The virtual service can also be integrated with existing on-site GDX servers using the company's base command software. Pricing starts at a cool $37,000 per month. But again, if you're a company that wants this, you might feel it's well worth it. Kind of a bargain if you're looking at a comparison to something like a physical DGX server, which will run you $200,000. DGX servers are typically used in AI-related workloads, including large language models or LLMs and generative AI. All right, Terrence, let's talk about some layoffs and what they might mean to things that we love. All right. Yesterday, DTNS covered Amazon performing yet another round of layoffs that have been coming in waves since last November. Sometimes it isn't clear to the outside of what exactly is being cut inside of a company of Amazon size when thousands of people lose their jobs at once. But today, we have a direct casualty.  In fact, this was a big, big, big, sad conversation we were having in our team discord this morning. Rich Strafilino said, this is big news, guys. And yeah, if you're unfamiliar with DPReview, you likely are if you're one of our listeners. But DPReview has been around forever, at least in internet times. It was founded back in 1998 and operated independently for 12 years before it was bought by Amazon back in 2010. At that point, the DPReview team, which operated out of England, was relocated to Seattle to be closer to Amazon headquarters, all made sense at the time. Now, since 2010, fewer people buy standalone digital cameras, especially because we've got smartphones that do pretty great things. But for those that do, and there are many people that do, a website like DPReview that goes above and beyond the in-depth is essential and welcomed. It's sort of, I guess like if Wirecutter reviewed every digital camera on the market with exhaustive details on image quality and specs and features and video reviews who love and live and breathe camera gear. But DPReview never really evolved under Amazon. A lot of people wondered, well, how will it get incorporated? Never really did, at least into any overall business model that Amazon put forth in a significant way. Now, Roger, I know you were an enthusiastic eyeball-share with DPReview, so why do we think this happened? What went wrong here? I think the biggest one is what you mentioned. Since 2010, at least for the Japanese camera manufacturers, the sales between 2010 and 2021 dropped 95%, like the number of shipments that they made. So there is significantly less money in that space than there used to be. So when they picked up DPReview, and DPReview, along with Imaging Resource, was one of the big go-to sites back in the early 2000s for anything related to digital cameras, whether it was lenses, accessories, flashes, hot shoe adapters, anything. It was really, really good. It was a valuable resource and what was fascinating is when Amazon did buy them, and as you mentioned, they didn't really integrate them in a tightly knit way. The site still existed as a stand-alone site, although if you were shopping for digital cameras on the Amazon site, you would see DPReview recommends this camera or this set of cameras. If you were looking, say, at a mirrorless camera or a digital SLR, it would have these recommendations, but it never really went further than that. And I have suspected for a long time, part of it was just because of the affiliate links that used to come from that site were tremendous. Like, they would have ones, not just for Amazon, but for B&H and a couple of other online stores that used to get tremendous traffic, because they were the go-to site to go if you wanted to buy a new camera. But before you plunked down $5,000, $6,000, $1,200 on camera, you wanted to make sure what you were getting was good. And there were very few other options out there, and DPReview was so good. So really, I think it's just a shift in the fact that the market has dropped, at least for consumer cameras, not so much for professional digital photography. In Amazon, it was just like, oh, well, we got what we wanted out of them, and we need to cut back since we're already having layouts. It kind of makes business sense in that way, although I'm sure a lot of camera enthusiasts are probably shedding it here, because it was still is, you have until April, still a great resource if you are in the market for camera accessories. Speaking of shedding the tear, I wonder if the employees or the people behind DPReview kind of saw this coming. I mean, we mentioned everybody going to smartphones, not using digital cameras as much, the site never being fully integrated into Amazon. I wonder if the people were kind of like, all right, any day now, any day now it's coming, let me figure out something else, let me figure something else out, because this is coming eventually. Yeah, I mean, I know, I don't work at Amazon, never have, and I don't really know what went on with DPReview specifically, but I just feel like, okay, we had 12 years, 13 now, to kind of figure out how to, let's say, Amazon, I type in digital camera for daughter, something like that, I'm going to get a bunch of results, maybe something that DPReview said, this is the camera that you want, and maybe it's at a higher end type thing, but here's why, yada, yada, yada, maybe that's one of the options, but there will be lots of others, because that's Amazon's business, right? And there are lots of reviews, some of which may be helpful, some of which may not be, you know, there's a whole bot thing going on when it comes to reviews on Amazon, which is not unique to the electronics category, but to have some sort of like the pro-corner type thing for certain categories like digital cameras, which more and more, I guess you could, I'm not going to call it like a niche market, because we're not there yet, but more and more is something where it's like, if you're an enthusiast, this is still a product category that makes a lot of sense to you, unspecs really matter, but the fact that Amazon didn't do anything with that, you know, it's in an ego year or two with something like that going on, fine, but it almost seems like, and the TechCrunch article that talks about the fact that DP Review is now gone, it's sort of worth it because the writer is pretty bummed out about it and just said, I don't even know if Amazon knew that it bought DP Review, that's how much it didn't leverage it in any significant way. And you know, it's weird and kind of crass, maybe to mention it, but at the end of the day, if you're buying something and you buy it through Amazon, Amazon's happy, right? I don't think that's crass, I think that's not cool. And what DP Review meant to them was really just another way to kind of funnel people into their store. Sure, yeah. And if they kind of get lost along the way of products, what does it matter if they end up buying something? And what it means to other people, well, that's a sad thing, but when it comes down to it, as long as we're making the money and we can cut what they see as fat, things like this are gonna happen. Well, as we mentioned, a lot of folks, myself included, who are camera enthusiasts, definitely photography enthusiasts, but are pretty much just rockin' the smartphone day-to-day these days. New flagship phones are always kind of exciting when you look at specs. The latest, OPPO announcing its new flagship phone, the Find X6 Pro, offering 2,023 flagship specs. That would be this year, including a 3168x1440 AMO LED screen, IP68 rating for water and dust, and support for 100-watt wired charging. Also featuring three rear Hasselblad branded camera sensors, each offering 50 megapixels. Main camera offers a 1-inch Sony sensor, also includes an ultra-wide and a 3x periscope zoom telephoto lens, shipping in China on May 24th, starting at $6,001, which is about $873. Sounds like a steal for those sorts of specs. We don't have word on international availability, but when to watch. Speaking of new features, Google updated the Pixel Watch to add fall detection feature, which will automatically detect hard falls and automatically contact emergency services. Hopefully they have tested the roller coaster thing that the Apple Watch went through recently. The update also adds the ability to press the watch's crown to see the time, even when it's powered off or otherwise out of battery. So we got a new smartphone. We got a Pixel Watch update. Terrence, I know you're an iOS user. I am as well. You're also the co-host of the Snoboes podcast. So you talk about specs a lot. Flagship phones from various companies increasingly have similar specs. You kind of start getting into like, well, for the price, what's better? What's right for me? What ecosystem am I in? And there are specs that are, I think, really important to my life. And there are specs that I go, oh, interesting, but maybe kind of gimmicky. What is your take on when you see something like this? Some new phone that gets rolled out or an update to wearable, for example, what are the specs that mean the most to you? Yes, you're right. We've been doing a lot of specs when it comes to our own podcast, especially as it relates to iPhones. But we've started to pare down a lot of the specs where we're not going over all of the specs because what I've noticed is that people care less about the specs as long as when they go to do something on the device, it's just there. And what I mean by that is like, for instance, we'll take the fall detection feature for Google. Nobody wants to say, all right, I've got this watch. I'm about to go hiking. Let me turn on my Google watch fall detection feature. Let me make sure it's up to date. Let me make sure I got it all set up. Make sure I got everything going. They just want it to work. So when it comes to actually deciding what they're going to buy or deciding do I need this extra feature, I think it's more of does this feature justify the cost that I'm about to spend for this device, but when they actually get it, they're not actually going through and setting everything and adjusting everything to actually say, okay, I bought this device for this feature. Let me go in and tweak it to work to my specific use case. They just want to know it's there. And they want to say, okay, I spent eight, nine, ten, eleven, twelve hundred dollars in a lot of cases for this new phone. It's got these new features, but I really don't care that much as long as they just work when I actually use it. So that's what I've kind of noticed when dealing with our own reviews. It's like, yeah, I need it to justify the cost, but I really don't care as long as it just works. You know, just based on our previous camera discussion, besides everything being behind me on my little workbench, I haven't used DSLR in years regularly anyway. Everything is now baked into the phone, but at the same time, even that has changed. First of all, the phone sensors have gotten better, and there's a lot of stuff built into the phone itself. So there's less reliance on, I don't know, cool filter apps. I mean, I've got 30 filter apps on my iPhone that I'd never open anymore because I don't really need them because the iPhone does everything itself. It wasn't always the case as the resolution has gotten better and better with photos and videos, and we have more options. I feel like that's sort of the killer spec. Now, I know a lot of people who don't really take a lot of photos at all and don't really care about quality. You know, there might be some photos taken of the family, you know, during the holidays type thing, but there's not so much emphasis on this. I think where a lot of people, that's where something like the new Oppo phone, the X6 Pro, the Find X6 Pro that I just mentioned, you know, a lot of people are going to say like, for less than a thousand US dollars, that is an amazing camera that you have. That's also your phone. That's also the way you might pay for things and, you know, this and that, and just, you know, takes up less space. I don't know. I wonder when digital cameras will be like, you know, the vinyl people where, you know, there's a resurgence because it's kind of cool rather than necessary. Definitely, and I'll add this real quick, especially in the smartphone market, if you're not an iPhone or you're not a flagship phone from, like, Samsung or even Google's Google Pixel line, you really just kind of spam specs because you want to impress potential buyers because as Terrence said, most people don't really understand what all the specs are, but they know big must be better. You're faster. Yeah, so you're just trying to check all the boxes, you know, that people go up to the car dealership and they see, well, this car has like 25 things that are standard feature and this one only has 12. And so you're trying to play to that value judgment for possible consumers, whether or not they might use it, right? If you're a critical buyer, you're like, well, I don't really need that because how often do I take pictures?  That's right. Well, if you have an idea of what you would like us to talk about on our future show, one way to let us know is using our subreddit. It's a great little community over there. Submit stories and vote on others, get them up to the top so we see them more easily, dailytechnewshow.reddit.com. All right, Terrence. I hope you're ready to talk about AI because it won't stop. Sometimes I feel that way. When I open up my browser in the morning, I'm like, oh boy, here we go again. But the hits keep coming. Microsoft announced it began rolling out its Bing image creator to Bing preview testers. This uses OpenAI's Dolly model to generate images directly within Bing chat. And you might say, well, which one? Microsoft didn't say which version of Dolly it's using here, just that it's using the very latest Dolly models. The feature will only be available through Bing's creative mode, coming to Bing's balanced and precise modes in the future and will roll out to the edge sidebar. That actually confused me a little bit this morning because you have to be over in the creative mode. Each request will generate four images from a prompt, each with a small Bing watermark in the lower left corner. Bing says, we want everyone to know we helped you here. Bing is also getting two new search features, visual stories and knowledge cards 2.0. The knowledge cards used to function like Google's knowledge panels, more or less. But now we'll include AI generated infographics and more interactive elements like charts and graphs and timelines. Not to be outdone. We have a new contender in the AI arms race. Adobe announced a beta of Firefly, what the company calls a, quote, family of creative, generative AI models. At launch, this includes two models. One offers text to image generation. Another generates stylized text. At launch, Firefly will operate as a standalone web app, but the company plans to integrate the models throughout this creative suite. Adobe said all training data for its models either came from content out of its copyright, was licensed for training, or was in the Adobe Stock Library because of course they want to make sure that people know they are not stealing artists, not stealing their work because that's been a big deal when AI first started popping out. Yeah, no kidding. And yeah, if you're an artist saying, what Adobe is claiming is either not true or not good enough for me, please do let us know because that's interesting. I am an Adobe user. I fire up Photoshop a couple of times a month to do this or that. I am not well-skilled at all and I'm not really using much more of Adobe's creative suite. But when I do, I kind of know how to do what I know how to do and everything else is either start Googling or ask somebody who's better at this than I am. Both tend to, you know, surface results that I'm looking for, but it's time consuming and a little cumbersome and to have anything, especially for stylized text or at least give me an image that I can start playing with rather than build all these layers myself. That's awesome. I mean, I see nothing wrong with this as far as somebody who's kind of more of a tinker than an expert. If you're more of an expert, I can see where you kind of go like, now where are we going to get all these folks who don't really know what they're doing? They didn't go to enough classes in graphic art to have these sorts of tools. It's kind of the same conversation that we've been having for a while is, are these tools good for the folks who need the help or do they end up hurting the folks who are better at it in the first place?  It was the big thing. And don't go look at my old blog post. Also, I'm pretty sure, yeah, but I'm pretty sure I copyrighted some images as a thumbnail for my blog post. So I could definitely see, you know, Firefly something like this coming in place to where I don't really want to get into the habit of, or I really don't have the time to create a whole image for this blog post that I just wrote or to make it relevant to today. Let's say I'm a YouTuber and I went all through all this effort to shoot the video, edit the video, add all these things. Now I gotta go and make a thumbnail. I can see people, give me a picture of Lama, like you said, with sunglasses. And that's my thumbnail. You know, I could definitely see that happening to where it's like, I don't have to put a lot of thought in it. But I needed to where nobody can say hey, you stole my picture, you know, but I can do it real fast. Like, if you're in a multi disciplinary setting, say you're making motion graphics or you're doing a video and you need to make the title sequence, you need to make the bumpers and all that. Oftentimes you kinda have to start from scratch. You gotta generate, you know, in After Effects you gotta make your shapes or you pull in assets from Photoshop and if you pull in an asset oftentimes you're not gonna have a vector image you're gonna have a raster image so if you try stretching it or resizing it's gonna look weird. I think this will allow people to essentially just build and create and basically simplify a lot of the initial setup work to building whatever they need to do whether it's a larger composition or a larger piece to finish work because oftentimes it's like looking for a tool when you're working on your car, it's like where's that screwdriver, where's that socket wrench that I need that one specific size for that I don't have and then you try to figure out something with what you do have this I think will simplify that product. This will also I think help a lot of individual contractors who might not have the budget to maybe hire a few more people to help them with the project and they have to do it all solo. This I could see being a very, very valuable tool. That's a good, that was kind of what I was getting at. In the past I've had people say, hey we want to hire you for this freelance project, can you do this? My answer is yes I can in my mind I'm like I don't know how to do this but I know who does and I'll work it out with them kind of thing because you want work. For me to say I don't know how to do it but I can figure it out with a bunch of built in tools so it's more of me just kind of having some fun within menus rather than farming out actual work to other humans with the other humans that wanted my work maybe aren't so excited about this but yeah this does streamline a lot of things. I think that's sort of the takeaway. So thank you Microsoft, thank you Adobe and thank you to all companies who give us AI stories every day because like an atmospheric river it never seems to end. No time soon anyway. Well hopefully you're not underwater and if you're not you might be excited that Acer, Acer the PC maker is hitting the road. Yep they announced their new E-Bike called the E-Bi E-B-I-I 35 pound bike so pretty light offering a 250 watt front spoke motor with a top assisted speed of 15 miles per hour and a 68 mile range no kind of fire on this thing. Acer says that the bike will adapt to a rider's preferred level of assistance and riding conditions over time so it wants to get to know you forthcoming companion app for the bike will do proximity based locking GPS positioning some fun stuff like that and it is for Acer after all so the bike's removable 460 watt battery can be used as a giant USB-C battery if you so choose. We don't know anything about price yet or availability but Terrence it sounds kind of good to me. It does. I was trying to figure out what's my use case or could I use this and not me personally but my kids I have junior high and high school aged children and their schools are like literally right around the corner and I dread every morning having to fight traffic just for a five minute ride so Acer may be getting my money if this is a price right so I can get my kids their own wheels until they are begging me to use my own which I'm not looking forward to that at all. I also love and I know Acer's not the first company to do this but also saying like and when you're not using your bike this is a great battery for all your computing needs you know charge your house. That's a pretty smart play if you think about it. Acer's just known for PC laptops, PC accessories you know that that markets like the digital camera markets slimming down a little bit what better way to kind of segue into a different market than the e-bikes which is you know on the uptake as Ristrafalina would tell you. Rich loves his bikes. And selling it not only as a means of transportation but additional power you know even even when you're not riding it it's still useful. Indeed. Alright got a couple mail bags let's check it out now. This one comes from John and Terence if this doesn't make sense to you I'll try to clarify. We were talking about the idea of having well we're not going to make it up but the idea of some expert saying we need a single lunar time zone so you know various companies, various governments people going to international space station got to talk to each other what are we doing up there let's have one singular time zone but that's kind of an issue because the moon doesn't have the same you know the number of hours in the day that earth does etc etc anyway John says that discussion reminded me that way back when Swatch yes the watch maker had this idea that the whole world would use internet time dividing a day into 1000 time units for example a new time unit would be called a beat instead of dividing the virtual and real day into 24 hours and 60 minutes per hour the internet time system proposed by Swatch divided the day into 1000 beats each beat is a minute and 26.4 seconds there was a new meridian internet time would be based on a new meridian opposed to the Greenwich Meridian for example the new meridian going through the Swatch's business in Beale, Switzerland called the BMT meridian the BMT would be the reference for internet time so you've got Beale mean time or BMT another invention of Swatch linking up to the central European winter or standard time which is UTC plus one hour when it's midnight in BMT the internet time is 0000 beats and noon is 500 beats Terrence there will be test later did you catch all of that absolutely not so do all these roll into one time zone or is it the idea is that the earth would all operate on a time zone that is I don't know more time focused than what we've all just gotten used to instead of having a bunch of time zones we would all use this time zone but instead of having hours and minutes per day it would be beats I guess my question is if it's just one zone do we need to call it a zone yeah I mean it's mean time at that point it would just be time wouldn't it yes time relative to where you are but it's always the same time is your four o'clock dark mine might be there would be I think there would be a lot of friction over choosing what the new meridian would be I see the rest of it sounds sort of useful although because it's not an integer the seconds aren't an actual integer but a fraction of one confusing for people who are converting but really the sticking point would be the meridian who gets to be the meridian Swatch said where our headquarters is so yeah of course you'd have to buy into that for anything like this to work but and I used to have several Swatch watches in fact remember the Sniffy Band back in the day they didn't last forever but yes John thank you for bringing it to our attention and maybe be nostalgic for anybody who says oh yeah I remember that whole Swatch idea what a fun gimmick and spec well someone who isn't a gimmick is you Terence again so thanks for being with us today let folks know where they can keep up with everything that you are working on yeah sure sure sure you can find me like we mentioned earlier in the show me and my co-host Anika Montford we do an in depth of all things Apple at thesnoboscast.com we talk about Apple we talk about a little bit of tech and some cultural things that interest us in addition to that myself Rob Dunwood who's been on the show multiple times and Stephanie Humphreys the tech John which is a tech show from our read black perspective so definitely check that out and we definitely appreciate all the viewers all the people who came from DTNS and vice versa who definitely want to say thank you for that well thank you for being with us always a pleasure to have you on the show we also have another thank you to give out and that is to our brand new boss named Mark Mark just started backing us on Patreon we'll see you Mark and we thank you speaking of patrons stick around for our extended show Good Day Internet we roll right into it when DTNS wraps up we're gonna talk a little bit more about Nvidia's AI announcements and I might talk a little bit more about scratch and sniff watch bands but just a reminder we do this show live and you can catch it live Monday through Friday at 4 p.m. Eastern at 2100 UTC those are the time zones we're using please for now find out more at dailytechnewshow.com live we're back tomorrow do it all again with Scott Johnson joining us talk to you then take it easy this show is part of the frog pants network get more at frogpants.com Simon Club hopes you have enjoyed this program


Hi and welcome to the session. Let us discuss the following question. The question says, find the area of a rhombus whose site is 6 cm and whose altitude is 4 cm. If one of its diagonals is 8 cm long, find the length of the other diagonal. Let's see its solution. Now first of all, we know that rhombus is a parallelogram equal to sites. So that means we can use the formula of the area of parallelogram to find out the area of rhombus. Parallelogram is base into height. Area of rhombus will also be equal to base into height. Now in question we are given that the site of rhombus is 6 cm. So here we can take this site as 6 cm, altitude is 4 cm. So altitude means height that is 4 cm. So let us substitute the values and find out the area of rhombus base that is 6 cm into height that is 4 cm. So this is equal to 24 cm square. Now we also know that area of rhombus is equal to 1 by 2 into D1 into D2 where D1 and D2 are the lengths of diagonals, the length of one diagonal that is 8 cm and we need to find the length of other diagonal. So let us suppose that D1 is equal to 8 cm and we need to find D2. Now let us substitute the values in the formula area of rhombus equal to 1 by 2 into D1 into D2. Now we already have the area of rhombus that is 24 cm square. So 24 equal to 1 by 2 into D1 into D2 that is 1 by 2 into 8 into D2 will get cancelled by the common factor 2 and we will get 24 equal to 4 D2. Dividing both the sites by 4 we will get 24 upon 4 equal to 4 D2 upon 4. So here 4 and 24 will get cancelled by the common factor 4 and here 4 and 4 will get cancelled. So we get 6 equal to D2. Therefore length of other diagonal is equal to 6 cm. Therefore the required answer for this question is first that is area of rhombus 24 cm square and second that is the length of the second diagonal that is 6 cm. With this we finished this session hope you must have enjoyed it. Goodbye and take care.