This lesson is on related rate problems. When you do a related rate problem, you are computing the rate of change of one quantity in terms of the rate of another. There are certain strategies that I have already written up for you, but let's go over them once again. The first one is to read the problem carefully, not once, not twice, but many, many times until you begin to understand what is going on. And as you begin to read it over and over, you should draw a diagram and write down what you know and what you have to find and also when you have to find it. And we will be doing lots of problems on this and we will follow this pattern every single time. The next thing you need to do is take the derivative with respect to the independent variable, which is usually t. And then you substitute in the given values and solve. For every problem you are given, you really should follow these strategies because they will help you solve the problem correctly. Our first problem is the soap bubble or balloon problem. And it reads, air is expanding a soap bubble so this volume is increasing at the rate of 10 centimeters cubed per second. How fast is the radius changing when it is 10 centimeters? And that means the radius is 10 centimeters in this particular problem. Well, what do we know? We know that we need the volume of a sphere and we will get that formula in a minute. And what else do we know? Well, we know the change in volume, which we write as dv dt, and that's equal to 10 centimeters cubed per second. The volume of a sphere is volume equals four thirds high r cubed. What do we need to find out? We need to find out the change in rate over the change in time. So that's dr dt when r is equal to 10. So we know that the volume formula is four thirds pi r cubed. We take this derivative and dv dt, remember we're taking with respect to t, becomes four thirds pi times 3 r squared dr dt. Again, the derivative is taken with respect to t. Cleaning this up, we get 4 pi r squared dr dt. Now dr dt becomes dv dt over 4 pi r squared. We know dv dt is 10. We know that r is 10 and we're filling those into our formula. And eventually we can reduce this and get 1 over 40 pi. So it's approximately equal to 0.008 centimeters per second, which is pretty slow. So this is how you would solve a balloon type problem. The next problem is a cylindrical tank problem. And it reads, how fast is water level dropping when the radius is 30 centimeters in a cylindrical tank when it is being drained at the rate of 3,000 centimeters cubed per second? What do we know? Well, we know the volume of a cylinder and we need that. So the volume of a cylinder is volume equals pi r squared h. And we also know that dv dt, the change in volume of the change in time, is negative because it's dropping negative 3,000 centimeters cubed per second. What do we need to find? Well, again we need to find the change in height over the change in time and again we're given when the radius is 30 centimeters. Of course, you know with a cylinder the radius will always remain the same. So let's go for our solution. Well, let's draw a diagram first. We know that that radius is 30. So when we develop our equation, volume equals pi r squared h, we are filling in for that radius because it is constant throughout the problem. So that is equal to 30 squared pi h or 900 pi h. When we take the derivative dv dt, we have 900 pi. When we take the derivative on h, it becomes dh dt. And we know what dv dt is. It's negative 3,000. So we divide that by the 900 pi and we get dh dt. So dh dt is equal to 30 over 9 or 10 over 3 pi centimeters per second. These first two problems are relatively simple because we've just taken the derivative with the formulas that we have had. Let's go on to something that might be a little bit more difficult. And this is a right triangle type of problem. A boat is being pulled to a dock at the rate of 2 feet per second. The pulley is 8 feet from the water and the rope is tied to the boat at 1 foot above the water. How fast is the boat approaching the dock when it is 20 feet away? We have a little animation on this, which we can show you. The solution to this right triangle type of problem is to first draw a right triangle. So let's draw a right triangle. We know certain things. We know that the distance from the rope to the top of the pier, where the pulley is pulling it in, is 7 feet. We don't know the distance from the boat to the pier. And of course, we don't know how far the rope is out. So we'll call the first distance x and the second distance z. So now we can use Pythagorean theorem on this because it is a simple right triangle. So we'll have x squared plus 7 squared is equal to z squared. Take the derivative on this and we get 2x dx dt. Again, everything taken in a relationship to t. 7 is a constant. And when we try to take that derivative, we know it's 0, so let's not even write it in. And then we'll have equal to 2z dz dt. We can cross out the 2s and solve for dx dt and get z dz dt over x. Now we can fill in for the numbers we know. We know that in this particular problem, x is going to be 20. We know that dz dt is equal to 2. Right now we do not know z, but we can find it by just putting numbers into our right triangle. We know that x is equal to 20 when we are trying to find our answer for dx dt. So now we have a right triangle with two sides known and one side not known. And using Pythagorean theorem, we find out that z is equal to the square root of 449. So we can fill that in the square root of 449. So now we get an answer of, this can be reduced, the square root of 449 over 10, and that's feet per second, which we can change to its equivalent decimal form in three decimals, 2.119 feet per second. That is a right triangle problem. Let's go on and do another type of right triangle problem. This one reads, two trucks leave a depot at the same time. Truck A travels east at 40 miles per hour, and truck B travels north, so they're traveling away from each other at 30 miles per hour. How fast is the distance between the trucks changing six minutes later when A is four miles from the depot and B is three miles from the depot? Let's put down what we know in this right triangle type of problem. We know that we have a right triangle, and it looks like the Pythagorean theorem is going to be involved in it. We also know that DADT is equal to 40 miles, and it's going in the eastern direction, and DBDT is 30 miles, and it's going north, and we need to find out DSDT, which is the change in the distance between them when A is four and B is three. So let's do our triangle. We have A going east, and we have B going north. So we have that DADT equal to 40. We have the DBDT is equal to 30, and we want to find DSDT when A is equal to four, and B is equal to three. Again, Pythagorean theorem, A squared plus B squared is equal to S squared. Take the derivative. Take the derivative on all three components, so we have 2A DADT plus 2B DBDT equals 2S DSDT. Again, canceling out those twos, we have this formula in which DSDT is standing alone. In this one, I'm just going to fill in the numbers for A, B, and S, DA, DT, DBDT, and then solve for DSDT. In the former problems, I actually worked out the DSDT before I filled in the numbers, but sometimes it's just easier to fill in the numbers first. So A is four, and we know DADT is 40. We know that B is three, and DBDT is 30, and we just need to determine what S is, because what we are looking for is DSDT. So if we fill in A is four, and B is three, we realize we have a three, four, five triangle, so that makes S equal to five. Solving for DSDT, we get 50 miles per hour. And if you want, you can do the math on your own and check this out. So this is the second type of right triangle where we have movement away or even eventually towards each other and some sort of triangle is being formed. Let's go on. This time we're going to deal with a conical tank. So this is a cone type problem, and the problem reads, a water tank in the shape of right circular cone has a radius of three meters and a height of six meters. If water is being pumped into the tank at the rate of four meters cubed per minute, find the rate at which the water level is rising when the water is four meters deep. Well, what do we know? We know the volume of a cone, and we all know that the volume of a cone is one-third pi R squared H. We know the relationship between the base and height of the cone, because we had said that the base of the cone is three meters, this is three meters, and this is six meters. So the relationship between the radius in the height is three, is to six. So the R to H is three to six. And we also know that the change in volume of the change in time is four meters cubed per minute. What do we need to find out? Well, we need to find out the change in height of the change in time when the height is four meters. In our solution, let's go back and rewrite that R to H is equal to three over six, which equals one-half. And the volume we know to be one-third pi R squared H. What we are looking for is dH dt. So our formula should be in H's, but we have this R here. So somehow we have to replace that R with something else. And it comes from the R over H formula, that relationship. So we can say R over H is equal to one-half, or R is equal to one-half H. And we can substitute that in for R in our volume formula. So our volume formula now becomes one-third pi one-half H quantity squared times H. And if we simplify this a little bit, we get one over twelve pi H cubed. Now we can take the derivative very readily. So we'll take dV dt is equal to three-twelfths of one-fourth pi H squared dH dt. Now we are looking for dH dt, that right there. So we need to substitute for the H and for the dV. And we find that dV is four. So we write that in and then copy down to one-fourth pi. And the H is four. So that's four squared. And then we have dH dt. Solving for dH dt, which isn't very difficult to do in this one, because I put a lot of fours in it, we get one over pi. And that's meters per minute. And if we want to evaluate that, we get approximately 0.318 meters per minute. Let's go to the street light problem. This time we have to deal with similar triangles. The problem reads a 6.5 foot man, six and a half foot man walks away from an 18 foot light pole at the rate of seven feet per second. We want to find two things. The first one is at what rate is the length of the shadow moving? And the second one is at what rate is the tip of the shadow moving? The first one is at what rate is the length of the shadow moving? And we are going to make the triangle for that one. If we create our triangle, it will look like this. We have this pole that's 18 feet tall with some light flashing on it. We have a man who is 6.5 feet tall, and he's walking away from that light pole. We also know that he's walking at the rate of seven feet per second. So if we call this x, then we know that dx dt is equal to seven feet per second. We are trying to find how fast this piece is changing, so we'll call that y. So we need to find dy dt. In looking at this triangle, we see we have a large triangle, and we also have a smaller triangle. So if we set up a ratio between the large triangle and the small triangle, we can get all our x's and y's in there and then take our derivative. So we can set up 18 over x plus y is equal to 6.5 over y. And now since we want dy dt, let's solve this for y. So we have 18y equals 6.5x plus 6.5y, or 11.5y equals 6.5x, and then y is equal to 6.5x over 11.5. Now we can take the derivative. So we have dy dt is equal to 6.5 over 11.5 dx dt. We know dx dt is seven, so we can put a seven in for that dx dt, and we find out the answer is 3.957 feet per second. This problem actually worked with the length of the shadow. And again, set up the right triangle, set up the ratio, and then solve for what you need. Now the next part of the problem is the tip of the shadow. The tip of the shadow is a little bit different when we set up our triangle. Again, we'll have the man at 6.5 feet, the pole at 18 feet, a little light on the pole. This is x and this is y. The tip of the shadow is actually the sum of x plus y, and that's important to know when you're doing these types of problems. That's your tip. We still know that the x dt, that hasn't changed, of course, is seven feet per second. What do we need to know? Well, we need to know the derivative of x plus y with respect to t. Now this problem becomes quite simple because of the fact that really the derivative of x plus y is the derivative of x plus the derivative of y. So we only have to add what we've already calculated together. We know dx dt is seven, and dy dt is equal to 3.957, and we add those together and we get 10.957 feet per second. So once you know the length of the shadow, so if you're given this type of problem, you do the length of the shadow first, you can easily find the tip of the shadow. And again, going back and remembering that in this type of problem, you look for ratios. So it doesn't have to be a streetlight problem or a length of a shadow problem to work with ratios. You should always consider that as you're working with different problems. Well, let's go to our final problem, which is an angle problem. This one's stated as Mario is standing 25 feet from a launch pad of a hot air balloon. If the balloon is rising at the rate of 20 feet per minute, how will the angle between Mario's eye and the balloon be changing after five minutes? This one's a little bit different because we have to use trig. So what do we know? We know that Mario is 25 feet from the launch pad. So we know x is equal to 25. We don't know y. We don't know z. But we need to find this angle here, which is theta. So we need to find d theta dt when t equals 5. We also know dy dt is equal to 20 feet per minute. So this is what we know that x is equal to 25 all the time. We also know the change in y over the change in t is 20. We're trying to find theta dt at a certain time when t is equal to 5. Let's go on to the solution. Well, the first thing we were given was when t is equal to 5. So let's translate that to something we know. Well, when t is equal to 5 and the balloon is going up at 20 feet per minute, then in five minutes y will be at 100 feet. So with our triangle, we had a 25 here. We had a y there. We were looking for theta. We need some sort of trig function that deals with opposite and adjacent. And of course, that's tangent. So we say tangent theta is equal to y over 25. We can take the derivative on this now. So we get secant squared theta, d theta dt, don't forget that, is equal to 1 over 25 dy dt. Now this time again, I'm going to solve for d theta dt and show you why. d theta dt is equal to, this would be 1 over secant squared on the right-hand side, but 1 over secant squared is cosine squared. So let's just write it as cosine squared theta. So we have cosine squared theta over 25 dy dt. Well, let's fill in what we know. We know dy dt is equal to 20, and we have our 25 sitting here. Now we need to find cosine theta. Well, at the point in question, we know, again, x is 25, y is 100, and we just have to find out what the hypotenuse is because cosine of theta is adjacent over hypotenuse. So the hypotenuse is the value 25 square root of 17. Why don't you calculate 100 squared plus 25 squared under the square root? So this becomes 25 divided by 25 square root of 17 quantity squared, and that evaluates out to 4 over 85, and since this is an angle, we do this in radians per minute, and that becomes in decimal form 0.047 radians per minute. This concludes your lesson on related rate problems. Good luck with doing them.


Hello everybody! In today's video, we'll discuss RAID system or arrays, what they are like, why people use them, and how to build such a system. Every year, computers' hardware is becoming more and more efficient and powerful. Central processors are developing more queries and threads, while effective frequencies of graphical cards are getting higher and higher. The typical speed of hard disks has long stopped at 7 to 200 rpm. Despite widespread advance of their even faster successors, SSDs, the new disk type has a relatively lower resource potential, and its reliability leaves much to be desired. That is why some users prefer the so-called RAID arrays or systems, which can increase read and write speeds almost twofold. There are various RAID times out there, some of them focusing on a speed boost and others improving reliability of data storage. In a few minutes, I'll tell you about all known RAID times and explain which are perfect for ordinary users and which are better suited for working with server equipment. You will learn about the reasons to have such arrays, how to build them, and what is required for this purpose. In our channel and blog, you will find solutions to any problem, from installing an operating system or configuring it to fixing possible bugs and errors or optimizing mobile gadgets. Our specialists will answer any questions you ask in your comments under the videos or articles. RAID is the abbreviation for redundant array of independent disks. This is a data storage virtualization technology that combines multiple physical disk drives into one logical unit for the purpose of data redundancy, performance improvement or those. To build the RAID system, you need at least two disks, but this number may vary depending on the type and purpose of the RAID array. This disk almost every decent motherboard comes with out-of-the-box support for SATA RAID. So let's have a closer look at RAID types. The first type is RAID 0. It is based on the principle of data striping. Data is split into blocks of similar lengths that get written across all the drives in the array. The main purpose of such system is to achieve actual disk performance to fault or even more. Wealthful disk capacity of all disks within the system is available. In simpler terms, it's like combining two or more disks into one big drive. The number of disks in a RAID 0 array is unlimited. However, if the disks are of different speed, the data exchange rate for such array will be determined by its slowest disk. In RAID 0, you can combine disks of any capacity. For example, a 500-gigabyte drive can be arranged to work with one terabyte or two terabyte drive and so on. For RAID 0, you need at least two disks. And here are the advantages of this array. Suppose you have two disks, each having the capacity of 500 gigabytes and the right speed of 100 megabyte per second. When combined into a RAID 0 system, you get one terabyte of space and a right speed storing to 200 megabytes per second. Such an impressive performance boost is possible due to distribution of data handling tasks between the two disks. In this array type, disks of different capacity and speed can be used, and in the end, their space and right speeds will be summed up. This array type is mostly used for storing temporary files. On the other hand, there is no point in storing a database inside a RAID 0 system, because even if one of the disks fails, the entire array is down. And you're going to lose all the information. It happens because data is written in turns to each of the disks, so a large file may be spread over the two or more disks you have combined into the system. Hence, RAID 0 has nothing to offer in terms of fault tolerance or failure protection. If you are running a system based on three or four disks and one of them fails, all the data will be lost. Summing up, enjoy the high speed, but remember to backup your data very often. Another type is RAID 1, which uses the principle of data mirroring. Data is written in parallel to the main or data drive and a mirror drive. In other words, data is written to the main disk and copied to the mirror disk. Each pattern of disk usage doesn't affect their performance at all, but only half of the total disk capacity is available. This array type is widely used in servers, because even if one of the drives fails, all copied data is safely stored in other drives, which act as backup storage. Such systems are meant for storing data backups and cloning critical information. Arrays of this type are quite reliable and can operate as long as there is at least one healthy disk in the system. The most serious disadvantage of RAID 1 is that you can use the capacity of one disk only, while you actually have two or more of them. Generally speaking, all other RAID times are on the variations of the first two kinds – 1 and 0. RAID 10 is a combination of RAID 0 and RAID 1. Data is written in parallel to two drives, while copies of such data are written to the other two drives. Such approach offers a performance boost and improved security for data storage. To build this type of array, you need at least four disks. In the end, you'll get double read and write speed if compared to single-disk figures, but only two disks out of four are actually available for storing data. Even if two disks fail at the same time, your information will not be lost. RAID 2, RAID 3 and RAID 4 are quite rare and less popular, as they make use of Hammond code for error correction, striping data at the bit rather than the block level and check sounds. In RAID 2, information is spread across data drives, just as in RAID 0. That is, it is divided into small blocks according to the number of drives. The remaining drives are designed to store ECC or error correction code data, which could be used for recovering information should any of the data drives fail. A prominent advantage of this RAID type is extremely high data transfer rates as compared to results achieved via single-disk. This RAID type is hardly popular in home systems due to the number of hard disks required. For example, in an array made of seven drives, only four of them can be used for data storage. As the chart shows, redundancy will drop as the number of drives grows. The main advantage of RAID 2 is the possibility to implement on-the-fly data error correction without sacrificing the speed of data exchange between the disk array and the CPU. Talking of RAID 3 and RAID 4, these two types are very similar in terms of architecture. Both require several drives to store data, and one of the drives is used exclusively as a dedicated parity disk. That is, it stores checksums needed for data recovery if a drive fails. To build RAID 3 and RAID 4, you need at least three hard disks. Unlike RAID 2, on-the-fly data recovery is impossible. Information can only be recovered after you replace the faulty drive, and it takes some time to complete. The major difference between RAID 3 and RAID 4 lies in the level of data striping. RAID 3 consists of byte-level striping with dedicated parity, which suggests a considerable slowdown in reading, writing large numbers of small files. On the contrary, RAID 4 consists of block-level striping with a dedicated parity disk, and every block is no bigger than a disk factor. As a result of its layout, RAID 4 provides good performance when dealing with small files which could be of critical importance for personal computers. This is why RAID 4 is more popular. A considerable downside for these two array types is the high workload on the parity disk, the one that stores checksums, which reduces its lifespan effectively. Another array type is RAID 5. It uses the principle similar to that of RAID 1. The biggest difference is that RAID 5 needs at least three drives, and one of them is used to store copied information. In this case, you will be able to use almost all disk space within the system except for the one disk used to store recovery data. In addition, you will get a performance boost, but don't expect it to be as impressive as in the case with RAID 0. This array type is best suited for specific tasks that involve large groups of hard drives. Suppose you have four disks to terabytes each. With RAID 10, you get disk capacity of 4 terabytes, double data read and write speed, and the opportunity to completely recover all the information even if two main drives fail at the same time. In the same scenario, RAID 5 will offer you 6 terabytes of disk space, a slight increase in write speed, and the opportunity to recover data from one damaged disk only. In this line, RAID 10 looks more attractive than RAID 5. Parallel to the small feat of two terabytes, you get high performance and fast recovery options. However, things do change a lot when you are going to use disks in great numbers. If you have 10 drives two terabytes each, with RAID 10 you only work with the 10 terabytes of space you can access. On the contrary, it's the huge 18 terabytes you can enjoy with RAID 5. All disks are available except the one that has to be sacrificed to copy data. As you can see, being able to use only 50% of the physical space seems too high a promise to pay for double speed and full recovery prospects. To many users, it looks more appealing to get a small performance bonus, lose only a small share of disk space and be able to recover data from any disk, provided that only one of them fails. Building RAID 6 array allows to solve this problem to a great extent. As array type allocates total volume of two disks for storing checksums, which are spread over different disks in a cyclic and regular way. Instead of one checksum, two checksums are calculated, which ensures data integrity even if two drives within one array fail at the same time. RAID 6 advantages are higher data protection and less performance loss, as compared to RAID 5, in case of recovering data after the faulted drive is replaced. The disadvantage of RAID 6 is a 10% decrease in overall data transfer rate caused by the growing amount of calculations required to generate the checksums and the increasing volumes of data to be read and written. So how do you go about creating a RAID system? There are two main ways – hardware and software. In the first case, you will need several hard disks connected to the motherboard plus a RAID controller, unless your motherboard already supports RAID. The next step is to enable RAID in BIOS settings. When you restart the computer, there should be a chart with more detailed RAID settings. If it doesn't show up, you may need to restart again and try pressing the key shortcut Ctrl plus I when the computer starts booting. If you use an external controller, it's likely you will have to press F2 button. In the chart, choose Configure and select the level you need. After the RAID array is created in BIOS, boot the computer, open disk management and format the unallocated space. This is the RAID array you have just created. For a software RAID, you don't need to enable or disable anything in BIOS. In fact, you don't even need your motherboard to support RAID. As we have mentioned before, this technology can be implemented with the CPU and the integrated operating system tools. This way, you can create a RAID 1 system. First click on the Start button and select Disk Management. Then click on any of the drives you have prepared for building a RAID system and select New Mirrored Volume. In the next window, select the disk which you want to mirror the other disk, assign the drive letter and format this new partition. In Disk Management, mirrored volumes are highlighted in the same color and have the same drive letter. Files are copied to both volumes. One first to one volume and then to the other. In this PC window, the array will be displayed as one partition. If any of the disks within the system fails, you will see an error saying failed redundancy, while all data in the second disk will be intact. However, it doesn't mean you should allow a bit of carelessness. When you create a RAID system, all data on the disk involved into the process will be erased. So before you start, make sure that important data is backed up elsewhere. And that is all for now. Hopefully this video was useful. Remember to click the Like button and subscribe to our channel. Hit the bell button to receive notifications and never miss new videos. Leave comments to ask questions. Thank you for watching. Good luck.


Welcome everyone. I'm Eva Ponte, Executive Director of the MITx MicroMasters Program in Supply Chain Management, and it's truly my pleasure to host this event where we will be discussing with Professor Josie Sheffi about the critical role of supply chains in business and society. Dr. Josie Sheffi is the Alicia Gray Professor of Engineering Systems at MIT, where he serves as the Director of the MIT Center for Transportation and Logistics. He's an expert in many different areas, but more specifically in systems optimization, risk analysis, and supply chain management, of course. He's the author of many scientific publications and nine books. It's truly a pleasure to have you today, Josie. Thank you very much for having me. My pleasure. Excellent. So during this life event, Professor Sheffi and I will be discussing the critical role of supply chains in modern societies, in modern global economy, for about 30 minutes. Then I will open the floor during 15 minutes for questions from you, from the audience. So please make sure that you use the Q&A feature in the webinar. So I can see the questions and bring these questions to Professor Sheffi and answer your questions towards the end of this event. The plan for this event is to discover how supply chain management plays a crucial, a critical role in almost every aspect of business. So my first question for you, Josie, is why is it important to learn about supply chains? Well, I think people, maybe people ask this question before the pandemic. I don't think too many people ask this question after the pandemic, because we found out as consumers, people in business always know, but the consumer found out how important supply chains are for sustaining life, for bringing food, for bringing medicine, as well as furniture and toys and everything else that you can imagine. So supply chains actually support not only sustaining life, but support standard of living. And the difference between countries with high standard of living, countries that standard of living is not that high, is supply chain efficiency in many, many cases. So it's also the difference between companies that do well and companies that don't do so well, because supply chain is responsible for having the items on the shelf, for having the items in the fulfillment center, for having the item get to your home, having the item be at the pharmacy, at the hospital, at the supermarket. And when supply chains are being hampered and not allowed to work as they usually do, with the usual efficiency, we have disruptions and we have shortages, like we had during the pandemic. Yes, thank you. Thank you for that, because it's true. The supply chain is kind of the backbone of these modern societies, helping everyone to get any goods. And you mentioned many different goods. Vaccines was one of those, medicines, toys, all of these goods. And you also mentioned the disruption of the pandemic. It's true that supply chains are interconnected systems and complex systems. And during the last, I would say, 30, 50 years, we have been observing many disruptions, many reasons that are kind of bringing complexity to the supply chain. And the pandemic was one of these big disruptions, of course. So can you illustrate or bring some examples of these aspects that you think are kind of bringing more and more complexity to the supply chains? Well, interesting, you mentioned it in my latest book. I talk a lot about it, trying to explain to the uninitiated, people who are not in supply chain, how complex and how intricate global supply chains are and how many entities and people and organizations and private, public, NGO are involved in getting a product. Think about it from the mind, taking the basic material or from the field when we grow them to a finished product. So in the book, for example, I follow a teacher. What happened to a teacher? And this does not even include all the processes from the cotton to the textile. But once you have a teacher, just to get it to the consumer, you see how many people, organization processes are involved in this. And traditionally, the role of supply chain was mostly high level of service, which means try to maximize revenue and reduce cost. This was complex enough, running it over a huge network over the entire world, crossing borders, crossing different legal regime, different regulatory regimes. This was complex enough in its own right. Now supply chain are expected, and not only expected, the only way you can achieve new goals like resilience, like the ability to withstand disruption, we talk about some disruption, is by strengthening supply chains or working in a different way in supply chain management. So regardless of the disruption, be it you know, Fukushima, earthquake and radioactive disaster or, you know, Katrina in the United States, BP explosion in the Gulf of Mexico, many, many fires now in California, floods in Europe, there are many, many disruptions all over the world. And so being able to withstand it and keep the flow of goods to consumers is crucial. Again, another new goal in the last 10 years is sustainability. Many people make mistakes by judging how sustainable, how green is a given company. That's almost meaningless because a company can outsource its dirty manufacturing operations to a country when the regulations are not that tough, when labor issues are not a problem. So you can have a problem both with environmental sustainability and social justice by just by reorganizing your supply chain. So you don't have to worry about what the EU thing, with the US thing and other country, but go to country when they don't pay attention to this. So in order to judge supply chain on many, many ground, you have to judge companies, you have to look at the supply chains, looking for example at how green a particular company is, is basically meaningless. You have to look at the entire process of getting from the mine or the field to the consumer, to the supermarket, to the home, whatever it is, what is involved in all of this. Are people anywhere in the supply chain using child labor? People anywhere in the supply chain using forced labor? Are people anywhere in the supply chain polluting the local rivers? Are people emitting CO2 in large quantities? Where it happened in the supply chain and so you have to look at the entire process. The basic approach at MIT in the in the micromaster is understanding the system and the system view of company operations. So you understand where the problems are, where the opportunities are as well, because we are focusing on problem, but there are also opportunities along the supply chain to make the entire chain more efficient, serve customer better, more sustainable, whatever. So this is a big opportunity and an interesting topic. I'm glad you mentioned this. The important role, not only the supply chain, the end to end supply chain, they understand the entire system. And this is one of the key things where I'm hearing from our learners in the micromaster program supply chain management, one of the things that they gain because they are exposed to the fundamental concepts in supply chains. So they are able to study about inventory management, transportation management, global supply chains, and at the end of the program they are able to connect the dots. And this dot connection, this overall view of the entire supply chain is one of the beautiful things I think that the micromaster program supply chain management is bringing to the society and to the world, which is great. So you mentioned the critical role. You mentioned many different important aspects. I'm going to try to deep dive in some of those. Regarding the critical role of that supply chains play in climate change, you mentioned this importance of the environmental impact of products end to end. For example, electric vehicles is a good example that we not only need to look at the end of the supply chain and how this is contributing to less CO2 emissions, we also need to look at the initial part of the process. So we need to cover the entire process, the manufacturing process, the origin of that product and not see only the end of that application, correct? As well as where the electricity is coming from. Because if the electricity is coming from fossil fuel, you don't get as much savings as you think you get. In countries where you can use renewables or you can use actually nuclear power, then it makes a lot more sense. Yes. There are also economic issues in general. When people think that if they are not polluting, will they drive more? I mean, it's just a phenomenon that's well known. When people buy cars that are less, that are more efficient in terms of the use of gas, they actually drive more because it's cheaper. So there's a lot of things to think about when you think about the entire system. Exactly. And all of the implications that are indicated on that. Another aspect I want to touch here talking about sustainability and this approach is the role of technology. How do you see technology as playing a key role when we are talking about sustainability? Because you also touch not only the environmental sustainability, also social sustainability and economic sustainability. So these three aspects, how do you see technology helping here, Josie? Okay. We need more time to look at it. Because I think in some sense, that's not the most important question. The most important question may be, will people accept? Will people be willing to pay a little more for a sustainable product? And so far, despite all the talk and the teenage girls from Sweden, people are not willing to pay more. Buy a lot in large amounts. There's always a minority that's an environmental minority that's willing to pay more. But by and large, people don't. So it's hard for companies to invest. It's hard for even government to set a regulation, even though people are trying for sure. In terms of technology, there are some interesting ways to think about it. For example, when we think about trucking, it turns out that autonomous trucking will have, most likely, a higher green impact than electric trucks. Because autonomous, because as it turns out, 30% or 40% of the fuel used by trucks is used for the benefit of the driver. And the driver has to sleep in the truck when the driver just has to cool and warm the cab. Once there'll be autonomous trucks, we don't have to worry about making the driver feel comfortable. So there'll be a big benefit in terms of emissions. Now, if you combine, of course, electric plus autonomous, it may be even bigger. But as you mentioned before, electric vehicles, one is to look at the entire system, not just at the, even at things like, I was just came back from London, and some of the cabbies are worried about Uber introducing autonomous cabs. And the question is, okay, let's say we have autonomous cabs, and they will be cheaper because there'll be no driver. But will there be a lot more trips because of autonomous cabs? Will there be a lot more congestion because of autonomous cabs? And there's so many impact. We know, for example, when something becomes cheaper, it is used more. It just demands supply. So it's, again, we come back to the system aspect. How will the technology, what impact the technology will have? Look, the technology like the renewables are an important technology. We have wind or sun power. These are technological breakthroughs that now become cheaper and cheaper, and we can use them more and more. But they have inherent flaws. They cannot provide what's called base load. They can provide it because the sun doesn't always shine, the wind doesn't always blow. So it comes and goes. And we need what's called base load that is there all the time, because you don't want to get your car into a charging station and then the charging station doesn't work. And by the way, we see it. We see it in California today. California today has brownouts, cases when there's no electricity for homes, because they invested a lot in renewable and shut down a lot of nuclear plants. There's no reliable energy. So we have to think about all these aspects. Exactly. And again, if we're talking about, you wrote again, talking about technology, you just need to evaluate the impact in the entire supply chain. It's not just a partial thing or a narrow thing that we need to look at. You also mentioned when I was asking you just about the complexity of supply chains, you just mentioned one of the basic tradeoffs that is in between achieving this high service level and low cost or do it in a very efficient way, correct? So there are many tradeoffs in supply chains that companies are dealing with then and trying their best in being efficient at the same time, trying to serve their customer, providing the best service to their customers. I want to connect here because Dr. Chris Campbell is in supply chain fundamentals. When he covered inventory management and transportation management, always at the end of the lesson, he's bringing this tradeoff in between cost and service that is one of the basic tradeoffs in supply chain, of course. And I also want to connect here now with e-commerce and omni-channel. We know that retailers like Walmart, Tesco, Target, big retailers are facing the challenge of combining stores and digital channels. They are trying to serve their customers at the store, at the carp site, home delivery and offer convenience, quality, value at the same time. So they are dealing with many tradeoffs. I was very positively surprised the other day when I was watching one of the videos of the president of Walmart that he was bringing supply chain playing a key role in all of this environment. In this competitive environment, this key role in order to help the company to be sustainable in all sense, in cost, environment and from the social perspective, of course. And we also know that these fluctuations in inventory create extra costs. And if you are managing appropriately the supply chain, then it's impossible to offer, for example, this seamless customer experience or these fast deliveries in an efficient way. So what are your thoughts here about these tradeoffs? What are kind of the most recent challenging tradeoffs that you are observing in companies in this environment and this dynamic environment? Okay, there are many, many answers to this, but maybe we can start with the consumer. Because today, many products you order from in Boston, from Amazon, you get it in two hours and four hours.  I mean, who needs the product in four hours? We order a product in the evening, it gets at 4am in the morning, it gets to our door from Amazon. So as long as people click on it and not, you know, they want it in two hours, they want it for, even though Amazon always says there's Amazon there, you can get it in three days, in two days, but it's just so convenient.  If I order something that they have in a fulfillment set and they get to me in two hours, it's very inefficient. It's not green at all, because they have to send it that event directly to my home and give it to me. They don't, it takes them an hour just to find it in the warehouse and then the event takes another, you know, 45 minutes to get to me. So it's just, there's no, they cannot build an efficient tour, which we'd like, but in any aspect of supply chain, there's this tradeoff. For example, let's say I make some stuff, some widgets, some items, customers ordering it. What I can do, one way to do it is to put everyone in a FedEx envelope and they'll get it the next morning. Another way is to wait and fill a truck and send it to the store. Clearly, sending in one at a time will be a very high level of service. The cost will be enormous. Putting it in a truck, I'd have to wait until I have enough to fill the truck. So I'm sacrificing level of service, but the cost is lower. Maybe I want to do something in between, something that will have relatively a high level of service and relatively low cost. But we have to think about all of these tradeoffs along the supply chain, how fast we want it, how good the level of service, at what cost are we, what is the cost that we are willing to pay. This goes beyond, I mean, it touches on geopolitical issues, it touches on reshoring, do we want, for example, have a supplier in China, which may take time to get to us, but it's a low cost, or have a supplier in the United States, which may be costlier, but we can get it quickly and it's not subject to problems. Because if there'll be, if the tension between the US and China will continue to grow, we may have more and more problems. And there's the geopolitical aspect. We saw what happened when the Russians invaded Ukraine, that suddenly there was a food problem, because Ukraine generates a lot of wheat and a lot of food stuff, so there are nations in Africa that were suffering. The supply chain of oil, when Russia cut all the oil and gas, most of the oil and gas shipment to Europe at the beginning, there was panic until they realized they can adjust. There are lots of adjustments to the supply of oil and gas and it was not a big deal and the winter is passing, no problem. A lot of these things are a question of trade-offs. And I'll give you the last example. In Europe, when there are very conscientious about green economy, about sustainability, it used to be until a short time ago that the oil and gas were considered dirty fuel. Just now, the gas is now green. Surely, gas has about half the emissions of gasoline, of oil, but it's not green, really. It's still a lot of emissions, but you see the trade-off. They had to agree, okay, so the change is not only between cost and service. Green and supplying energy to the consumer. There are many, many trade-offs. Yeah, definitely. I agree on that. And thanks for bringing even more examples just to illustrate this key aspect of supply chains. And also supply chains, and you brought to us geopolitical tensions, there are many aspects that are impacting and are intricate systems with many stakeholders. Many stakeholders that are involved across many geographies. It's a global problem, what we have. I want to connect here with the skills of the supply chain professionals. So what the skills do supply chain professionals need to have in this increasingly complex space? What do you think about that, Josie? Well, obviously, we teach what we think is important in the MicroMaster and in the programs at MIT. But we go from the fundamental understanding how supply chain work, understanding how the basic components of supply chains are working. What's involved in inventory management, in optimizing inventory, what's involved in transportation management? These are the basic building blocks of logistics. But we talk also about procurement, we talk about distribution, we talk about all kind of related issues. There's a whole level of knowledge that is just understanding what you have to do as a supply chain manager. What are the basics that you have to do? We do try, even in the MicroMaster, to instill some of these ideas of trade offs are everywhere. Supply chains are a complex system. You have to look at it end-to-end. They interact with other supply chains. They don't stand alone by themselves. How do you deal with disruption and unexpected events? So we also go to that length to give students the tool that they need to be successful in their profession. So I think I'm happy to open it to questions if you want. Yes, yes, definitely. Yes, I have a lot of questions in the chat in the Q&A. Yeah, we are going to go to that in a minute. I need to cover one more thing. But yes, I would use that in addition to cover these basic concepts in the MicroMaster. The system thinking, the problem-solving, the critical thinking is there. Supply chain fundamentals. Dr. Chris Cap is our alma mater in the MicroMaster program. He's definitely been in these trade offs since the very beginning. The very first time he's talking about supply chains, he's bringing these trade offs that Professor Sheff is bringing here. So that's important. I just want to bring one more topic because it's one question from Claudia. Claudia Cardenas and connect very well with my point here. Claudia is asking, in your opinion, how is artificial intelligence going to change the supply chain and our role, the role of supply chain in it? And I think it's a great question and connects well with this, with the skills we just have been discussing, Josie, because definitely I know that in your book you have this dilemma in between is AI killing jobs or creating new jobs? So I think probably we have here a very good question from Claudia about the role of AI and how this is going to impact and change supply chains. Well, okay. Nils Bohr, the famous physicist, says it's very hard to predict, especially in the future. So I will try to predict the future anyway. Look, in the new book, here's my new book. In the new book I talk a lot about the book is called AI and the Future of Work in the subtitle. And I look at all the industrial evolution and there were always tension. Everybody thought that there would be job losses. And they were, by the way, they were job losses. But what always happened, there were more jobs created than jobs lost. And job changed. Some job disappeared completely. I mean, we don't have elevator operators anymore. We don't have people use the phone exchange and put the staff when you try to call somebody automated. So some jobs were lost. Some jobs were de-skilled. People who use a lot of skill now require less skills. And some jobs were democratized. Think about the impact of, say, spreadsheets. It used to be if you wanted to build a model, you have to go to some a modeler in your company and write something Fortran or Algol or God knows all these languages and build a model and took back and forth many times. Now you just download the data you do yourself in Excel. Think about the impact of ChetGPT. First of all, you can write code, which means the managers will be able to write their own code without looking for programmers. Just, and this will bring immense productivity because you don't have to go back and forth between the person who programs and the person that that's not what I meant. I meant something that the person who understands the problem will write the code. In terms of writing text, of course, ChetGPT is still very far from perfect. It still makes up data and makes a lot of mistakes, but it will get better. And to me, it's a tool. It's just another tool. So we will stop judging people by how well, let's say, they write prose, but how well they use ChetGPT. Can they look over what ChetGPT created and judge it? Does it make sense? Does it not make sense before they send it to the next person? I find it myself sometimes very useful in terms of starting to think. So when I look at the new subject, I ask ChetGPT sometimes, I get one page of stuff and I say, yeah, that's just garbage. So I try to do something else, specify something else. But sometimes I get stuff that is useful and I can start this, start to work from there. So at the end, I think it's a tool. But let me add one more point about this. In every one of these technological revolutions, the problem is as follows. You know the people are going to lose their job because these are the people that you know. They do the job, they do the tasks that you know, the jobs that you know. They are cashier in the supermarket or whatever. What you don't know is who are the people who will do the new jobs. Yes. The jobs don't even exist yet. And you don't know what's required for the new job. But I would say don't forget that some things that it will be a long time before AI will be able to do things like empathy and morals and understanding context and being able to judge algorithmic results. I think that it will be a long while before AI can lose some people for a long while to the job. And again, the critical thinking you brought before as a key skill here because you need to have this critical thinking in order to interpret this information that you are receiving. This also connects. I'm glad that you are bringing this about the new jobs that these new solutions, new technologies are creating at the end of the day. This connect with the recent video from the presidents of Walmart. He was talking about the role of automation. He said, okay, automation is going to help customers, associates and companies business, of course. And he was asked about less manual labor, of course, less manual labor. But we might need and we are going to need different roles for associates are going to be required. New roles are emerging, less manual and most likely or probably better paid jobs because are going to require more skills and people more qualified in order to be able to do that. So yeah, this is totally aligned with that. Okay, so we have a lot of questions, Josie. So let's try to bring more questions. I have one question from Remy. Remy, he's saying that in May, mid-May, the European Union is organizing a major conference about beyond growth. Participants will discuss how to achieve sustainable prosperity in the European Union after growth has ended. Remy is asking, how can the supply chain supports prosperity rather than material growth? Okay. How do you define prosperity? That's the question. The European has a vision of industrial, the industrial revolution 5.0. It's beyond industry 4.0 because it looks at growth but sustainable growth and with social justice as well. Whether it can work, it's not clear. Honestly, it's not clear. It's not clear because the question is, who would invest? Ask yourself, would you invest in somebody who would come to you and say, you have two possible investments. This company will pay you more, will have better margin, higher revenue, lower cost, but it's not going to be that green. This company will sacrifice margin for being more green. Would you invest? The investment community doesn't work this way. They go for the highest margin. The question is, will they be able to have its cake in 82? They have some ideas on how to do it. Specifically, supply chain have to keep simply being as efficient as possible. When I mean as efficient as possible, I hope, and the European Union is working on this, on introducing the externalities emission, for example, into the equation, so being carbon taxes, various ways of carbon taxes. Because with carbon taxes, it's automatically, you will want to use less energy in transportation, in warehousing, cooling, in everything. So it works. The economic incentive and the sustainability incentive goes hand on hand. But I think it will be something that will be needed to be imposed from above. Because the supply chain or a company that will do it on its own will be less competitive. And in fact, the European Union is introducing, you know, border tax, because they are always afraid that, let's say, imports from China don't have any regulation. It will be cheaper. So they, even by the idea, they admit that without this environmental regulation, product will be cheaper. And they want to maintain the competition. So this is a move toward, it's just like carbon tax. It's aligning the economic incentive with the sustainability incentive. So once they do it, then supply chain will automatically respond. We don't have to do anything different. And different countries are using different incentives. And this is definitely another big topic here. Another question, Colin. Colin is saying, Professor Sheffi, thank you for the webinar today. In your latest book, The Power of Resilience. I don't think this is the latest. I think this is the previous one. But in any case, The Power of Resilience. The Power of Resilience is five books ago. Exactly. You talk about the challenges with forecasting during a crisis. Can you talk more about the ways you are seeing success with supply demand forecasting during a crisis? Okay. Let me talk about it, because this is tied to one of the, to the previous question about the role of technology. Yeah. Many companies are using lowest technology being, you know, machine learning and others in order to forecast demand. The problem during disruption, if it's a big enough disruption, there's a structural change in the demand pattern. And the algorithms fall apart. We saw it during the pandemic. We saw it during the financial crisis, Fukushima. The algorithms are falling flat. You cannot use them. Also, there are questions. We become more and more dependent on digitization. And we are more and more vulnerable to cyber attacks. And we saw how MERSC, for example, came to a halt doing a cyber attack. They were not even part of it. It was not directed in them. It was the Russian attacking Ukraine in 2017. MERSC came to a halt. This comes back to, we're talking about AI and jobs. We need people who can still understand the processes and can run it by hand. At the time in MERSC, they were writing manifest by hand, with the computer and faxing it to the various, you know, custom authorities, because the computers didn't work. But lucky, they had enough people who still remember how to do it. The question is, if we will have generations of people who just know how to know it on the computer, the computer does a lot of the calculation, not only they will not be able to work without a computer, they will not even understand the underlying process. What should be done in the first place? Not only how it's done. So companies will have to have a lot of people who understand the process, because people by nature are more flexible and understand the context and understand that you have to do things differently. You have to create new collaboration. You have to create new supply chain on the flight. Very hard for algorithm, AI, machine learning, whatever you want to do it. And in the foreseeable future, I don't think it will be possible. So we still need a lot of people to do it. Yeah. Understanding the processes and again connecting the dots, because you need to connect the dots with all of the implications. We have one question from Javier. Javier is saying, I'm a supply chain professional with more than 15 years of experience. What should I do to be a relevant contributor to the supply chains of the future? So maybe I can take this one and you can jump in. Will you take it? Yes. Yes. I would say, Javier, connect with lifelong learning opportunities. There are great opportunities now. Online education is is helping a lot to full-time professionals because are very affordable, are very flexible convenience. You can learn from videos whenever you want, during the night, during the weekend. So I think these online and asynchronous courses are very, very helpful. We are offering, not only the MicroMaster, we are also offering custom courses for companies like Walmart, C.H. Robinson, and the associates are finding these very helpful in order to just to learn and keep them up-to-date with new tools and techniques and just to bring these to their companies. So I just want you to add that. Yes. Let me just add something. It's not only our course online, other courses online, but it's also going to conferences, going to meetings with people, understanding what other companies are doing, trying to get yourself into lectures and presentations about new technologies, so at least you understand what's coming. The death nail of people is just if you don't keep developing, you must develop yourself, keep developing all the time. Yeah. Yeah, and conferences are great sources to keep you updated. Yeah, definitely. So one question, this is more a specific question from Danny Vasquez. He said, of course, thank you for the insightful meeting, wonderful points. He is highlighting the instant gratification and the risk about costs for satisfying those instant gratification demands. He's asking, what are your thoughts on drone delivery service that satisfy delivery within hours without using typical modes of transportation? Yeah, it's a very specific question about last-minute delivery, but we have the lab here, the last-minute delivery. We actually work on this. One of my colleagues, Matthias Wikingbach, is working exactly with a company, an actual company doing experiments with vans that are moving and the vans can send drones to do the home delivery. At this point, as you know, there are many, many regulatory hurdles on this. It's not clear that drone can fly freely when drop bombs on houses or come down, but it is happening, by the way. It is happening already in large part of sparsely populated like Africa. There's a company that does drone delivery of medical supplies. So there are companies who do it already. As I said, Dr. Wikingbach is here, is trying to do it, trying to see how it can be done in urban areas. Maybe not in New York City, but in suburbs, when you come to a specific home. I don't see how you can put it in the window on the 21st floor on Fifth Avenue, but it can be done in a suburb possibly. In terms of instant gratification, we have instant gratification already now. So this is just another mode of creating instant gratification. Maybe if the drones are electric drones, and I hope they are just for the noise that they create, if they are not electric drones, so many of them will be electric. So maybe it will be a more efficient way to get instant gratification. Of course, the main question is why do you need instant gratification? And that's part of education and just thinking about the issue. But by the way, government can step in. The government can step in and outlaw less than two days, unless it's a medical supply, or unless it's something threatened in life. Come on. For which type of product do you really need this instant gratification? Let me connect now. I'm going to combine two very good questions just to end the event. One from Bogdan. He's asking about what is your stance on technology? Are we going to share or to see companies sharing data end to end and collaborating? This is a great question. And I'm going to combine this with Pamela's question so you can answer both at the same time, because she's also bringing the importance of supply chain security in terms of the data in order to achieve technological advantage. So yeah, data privacy and data sharing among different actors in the supply chain is the question. I understand it's not so much data privacy. It's data security. The company want to keep the data. As people who were listening to our latest last week, we had a conference and one of the speakers was trying to put together a whole group of companies to create better forecasting and better cooperation. And the main problem is the lawyers get involved and data sharing and the whole idea is to share data without sharing prices, but just sharing, you know, total amounts of product orders and product receipts. It's a big problem. We are living in a competitive society and its companies are hesitating. They do it on the margin with companies that they trust. Look, along the supply chain, people do share data. Companies do share data with their customers and suppliers. They do share data. But if you're talking about making a big change, you need what's called a horizontal data sharing. So companies are even competing with each other will share data so we can get a better picture of demand or supply of what's going on in the marketplace. Because especially when something happens, when there's a disruption, companies start overordering and we have what's called phantom orders because they know that suppliers have to allocate and give 50% for each. So they multiply the order that they get, you know, higher number and it's not really ordered. So security, of course, companies are not willing to share because knowing the data is a competitive advantage. You know, my data, people know how much I order, how much I don't order, what's going on, how do I keep inventory, people can use it against me. So companies are not easily sharing data. Yes, they are not. So you see, with almost 400 people attending live, as you can imagine, we have many more questions. But yes, we are running out of time. So I really wanted to say thank you for a very insightful talk and sharing your experience with our program, with our learners. And thank you so much for bringing all of your experience here today. Thanks also to the audience for great questions. It has been a pleasure to host this event. If you want to be in touch with us, just reach out to us and we will be happy to answer your emails. Thank you so much. Thank you, Josie, once again. Sure.