 Valasai from Walton Institute of Technology. So, in today's session, we will discuss briefly about different OR models that is operations research models and their applications. At the end of this session, if we talk of the outcomes, students will be able to understand the different models in operations research as well as their applications in brief where and how we can probably use these different models. Now, talking regarding the actual types of models, there are various modes that we can think of considering these different models. The very first mode that we will consider is the classification based on the structure. So, under this particular mode of classification, we can have these three types of models, iconic models, analog models and mathematical models. Now, the very first one, iconic models as the examples are given, they replicate the actual product, the actual situation, whatever you are thinking that is replicated, it is scaled down maybe probably and it is exactly similar to what we aim at. So, the toy car, the toy aeroplane if you think of or the architectural models of some buildings, they exactly look like the architectural buildings exactly look like the real building. Then toy car or toy aeroplane, they exactly look like a actual realistic car or a airplane. So, this is what we mean by iconic models. The second type under this is analog models. Now, many times you have seen like we use graphical representations of the data wherein maybe on one axis we are indicating time and on second axis we are indicating the distance. So, it could be a graph between time and distance and we may indicate like 1 centimeter is equivalent to 1 kilometers distance or 1 centimeter on the graph paper is equivalent to 1 hour of a time something like that. So, we have some analogy of representing some parameters and that kind of a thing in graph that we observe is referred as analogous or analog models. We use some analogy to represent certain parameters and the third model is mathematical and these mathematical models example LPP is given here linear programming problems, inventory control, assignment problems, transportation problems, many models are there these we will discuss in brief little while later. So, these are the three models we have in all under this first mode of classification. Second classification is by the nature of the environment of the data you can say deterministic models or probabilistic. These are the two types these probabilistic models are also referred as stochastic models. Now, what does it mean? What are the data we are using in problem solving, problem formulation and problem solving? What is the nature of the data? Do we have certainty about the data that we have? Say for example, in LPP in assignment problems, transportation what are the models you formulate there you have some assumptions, some data to get very precisely maybe not possible. So, you assume something and take it like it is certainly that way. For example, if I give lead time you order something from Amazon or Flipkart kinds of these online businesses, so many resources are there as you all know nowadays everybody knows it. Now, what is the lead time to get that ordered material from that company to use? Since the time you order it what is the time that it takes to reach to you? So, that lead time now that is very difficult to really say exactly like in exactly 4 days it will definitely come not in 3 days not in 5 days that is not possible, but still within fairly good enough assumption you can have is like yes mostly 4 days can be a lead time. So, if you can assume it to believable extent to go ahead with the situation you can call that as a deterministic model and otherwise say take a case of paper newspaper selling boy then how many newspapers will you sell? Every book you will find this example of a newspaper boy how many papers that newspaper boy would sell in a given situation on certain dates, seasonality also affects these things your socioeconomic conditions, so many aspects are there. So, you have probability associated with the demand for such things, so those models will be referred as probabilistic models. At this point of time I expect you people to just list down some applications of these over models try to think of some actual situations now here we will talk about the third mode and that is on mathematical models. So, few of them we will discuss in little elaboration first is linear programming problem in this model if you have seen earlier video we had discussed the example of two wheeler company and how the methodology can be used in that. So, we formulated objective function from the variables of the problem we formulated constraints also and solving that we can think of either maximizing profit kind of a thing or minimizing cost kind of situations and this linear programming problem if I just give the example out of historic things in 1992 whatever the golfer we had during that the defense missiles used by Americans they were using software which was written based on linear programming. So, it has got lots of applications in many domains next model is assignment models this is something like you know you have 5 machines and 5 workers. So, each machine one worker you have to assign so it is a typical case in the industry or you have certain 10 jobs and 10 workers which job should be given to which worker. So, these are you are trying to assign one thing to other. So, this comes under assignment problems or assignment models. Third case is transportation models as we normally talk the mall culture you all know you are all used to that in every mall you have thousands of items. So, for example, if you take a tooth paste or a biscuit kinds of items then even in toothpaste you will have 10, 20, 30 varieties of toothpaste or even biscuits will have 50, 100 varieties. Now, each type of these items again are required in different quantities and they are bought from different resources different companies different warehouses. So, from which company from which resource from which warehouse which location by which mode should we transport that supply chain management is a very big field and every mall you know they use thousands of items in thousands of quantities. So, supply chain management and in that how to transport the items the transportation models that is logistics management also called as a very big topic and very highly demanded in today's time. Then is per CPM this is also called as a project management tool or project management technique. Here in a certain project in how much time we can complete and if we have to complete that in little less time how much extra we may have to pay these kinds of things you can deal with. For example, I can tell you ISRO or NASA types of people these organizations they launch different satellites. So, what time they can launch a particular satellite how much time they would take to manufacture a particular satellite. You listen to their mass mission or mission moon so many missions they do have and there in these people you know they plan for like a certain satellite they might be having a data which one they would launch in 2021 or 2025, 2030 at what time we satellite they would launch. So, that comes in project management and maybe in any ship building or any unique building construction you can apply these things. Then inventory control model every organization deals with some items some products and these products like for example, at home also your grocery items should you buy the grocery requirement every day or per week or per month or for a year. Similarly, in industry there are the questions which items in what quantity should be bought so that the overall inventory related costs are kept minimum. Then replacement models we have lots of equipments in the industry what time could be best to replace the equipment after it is subject to wear and tear. So, it is worn out then when should that equipment be replaced. So, such applications we have enormous in industry then sequencing hundreds of jobs thousands of jobs are there in the industry. So, which job should be processed first so that the idle time of the machines or the job also is minimized and the total throughput time you can keep short and non value adding the time you can cut down. Then games theory this is related to the strategic decision making aspects of the organizations and it is a very widely used technique again at top management level for strategic decisions for business games that is called as games theory. And this further integer programming non-linear programming dynamic programming they have got specific domains and certain set of assumptions and in those situations these different techniques can be applied given a situation. Then we have got simulation. Simulation is a technique wherein if nothing of this upper discuss models about discuss models can be applied then here you can apply simulation. You have to represent something similar to and nowadays lots of computer based simulation tools are available. So, OR has got you know a solution to every problem you take any problem under the sky OR can be applied to it. So, all that these models some of the other model in a given situation we can definitely apply if not simulation certainly can be applied to it. So, these are in all the different models we have again these are the three books Taha Sharma and Gupta and as usual again on net you can get lots of references. Thank you.