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Electrotechnische Vereeniging Issue 24.2 | March2021 PREDICTION, AN UNCERTAIN T Y Interviewwith Dr.ir. G.R. Chandra Mouli About EV Charging and load prediction Black Hole Visualization By Annemieke Verbraeck What is Quantum Computing? By Prof. dr. ing. K.L.M. Bertels
IN MEMORIAM We deplore to announce that has passed away at an age of 96 Prof. ir. Hans van Nauta Lemke Emeritus Professor and Rector Magnificus Delft University of Technology Honorary Member of the Electrotechnische Vereeniging * † November 22, 1924 January 10, 2021 Palembang ‘s-Gravenhage Since 1989 the Electrotechnische Vereeniging has had the honour of having Mr. Van Nauta Lemke as Honorary Member. Our thoughts go to all involved.
24.2 From the Board Dear Reader, Dear Reader, Another Maxwell edition is pub- students who are actively enjoying We have arrived at a new quarter. lished and thus another quarter has the ETV during these times. I don’t think anyone would have passed in this very strange time. It This year has taught me and the been able to predict the current has been tough for all of us. We are rest of the Board to make the best situation at the start of this aca- all familiar with the circumstanc- out of a situation that did not go as demic year. EWI has been closed es, and we all would like to have a anticipated because as we all know, for a few months now, and prob- taste of our old lives again. Just for this year played out differently than ably will be for a bit longer due to one day, to break free from the daily other years. fire safety issues. Luckily, there grind we have lived in the previous is light at the end of the tunnel, year to shake things up. A few weeks ago, the EEMCS Re- as experts expect the virus to be cruitment Days have taken place, containable by this summer. This Some of us have discovered new which to me was the most impor- means that activities such as the hobbies, some of us have found tant event this year. It is something first year weekend, the gala and a new love for being outside and I was extremely excited about and Lustrum activities are just over some have enjoyed watching lots I have worked towards since this the horizon. Keep your head up! of movies with their housemates. year started. If you have any questions or com- The pandemic has made us more Now this intense yet special week ments regarding your studies, creative and forced us to discover has passed, I have more varied du- know that we work daily from our new things we did not know about ties which means there is room to digital Board room on discord. You ourselves. work on new projects and coming are always welcome to join us for up with fresh ideas to introduce our a chat even if it is not study relat- A year ago I was asked if I were partners to the students. ed! up to the challenge of becoming a Board member of the Electrotech- Enjoy the rest of the year, and re- With excited regards, nische Vereeniging, and what an mind yourself to relax once in a Tim Plantfeber experience has it been so far! while. Secretary of the 149th Board of the Electrotechnische Vereeniging. When looking back on the past few With excited regards, months I see a lot of exciting activ- Floor Walterbos ities, a lot of new committees and Commissioner of External Affairs lots of of the 149th Board of the Electro- technische Vereeniging March 2021 3
24.2 Colophon Editorial Dear readers, Year 24, edition 2, March 2021 Welcome to the second edition of the 24th Maxwell! The theme of this Editors edition revolves around the role of electrical engineering in not only Yunus Emre Döngel building, but also predicting, our tomorrow. Merel Verhoef Aniruddh Kulkarni The power of prediction in the mathematical sciences, stemming from Natasha Birari the understanding of probability together with access to massive Nitish Kulkarni amounts of data, has become a cornerstone of modern scientific ap- plications. Unfortunately, in the public sphere, it has also given birth to Designers one of the biggest modern misconceptions about science: that scientif- Neil Dani ic outcomes are ‘conclusive’, whereas in fact, all scientific methods are essentially the understanding and art of ‘uncertainty’. Contributors K.L.M. Bertels, G.R. Chandra Mouli, For this edition, the Maxwell committee reached out to researchers Kees Pronk, Annemieke Verbraeck, who are working with prediction and uncertainty across diverse fields Simon Tindemans, Jan de Jong, in electrical engineering – from black hole visualisation to quantum Gijs Lagerweij, Tim Plantfeber, acceleration, to how data-based prediction is being incorporated into Floor Walterbos EV charging and the European power grid.v Advertisement We hope you will enjoy the articles we have brought together. A big page 32 Witteveen+Bos thank you to all our contributors for sharing their experience and in- sights. I also want to express my gratitude to the Board and my fellow Printing committee members, without whom this edition would not have been Quantes, Rijswijk, 1400 copies possible. Electrotechnische Vereeniging Natasha Birari Mekelweg 4 2628 CD Delft The Netherlands Phone number: +31 15 278 6189 Email: board-etv@tudelft.nl Website: etv.tudelft.nl 149th Board of the ETV President - Joris van Breukelen Secretary - Tim Plantfeber Treasurer - Vera Pauptit External Affairs - Floor Walterbos Education - Reinier van der Leer Subscriptions Non-members can get 4 issues of the Maxwell against an annual contribution of €10,-. Change of address Please send changes in your address to the (e-mail) address above or use the website. 4 March 2021
24.2 INDEX 6 The Hammer Computer 10 EV Load Prediction 14 Black Hole Visualization 20 A physicist who never lost her humanity 22 Student Columns 26 What is Quantum computing? 30 Possibly the D-Day March 2021 5
24.2 The Hammer Computer Kees Pronk At the Study Collection, we were structure of this analogue and aware of a large machine (3.0 x mechanical calculator. 1.5 x 1.0 meters) standing in a dark corner. The origin and purpose of The construction of this machine this machine had long been for- started around 1950. To really gotten. Fortunately, an observant know what we are dealing with, visitor was able to tell us where we must go back to that time to the device was built and who the understand the development of designer was. radar technology and the con- The device had been constructed struction of computers in those around 1950 at the Nederlands years. This whole exercise re- Radar Proefstation (Dutch Ra- sembles technological archaeol- dar Testing Station) in Noord- ogy: from the artifacts found, an wijk (now: Christiaan Huygens image is formed of the operation Laboratory in Katwijk) under the of the machine, like a puzzle be- supervision of its designer ir. J. ing slowly put together. A. Hammer (figure 1). A brief de- scription of the machine, as well The Hammer computer was de- as the author, is given in [3]. signed and built for a special pur- A literature study yielded two pose: the design and calculation Fig 1. Hammer’s articles. The first article [1] is a of linear radar antennas. With Calculator report by Hammer at a scientific radar transmission antennas, it conference in France, expound- is important to generate a beam ing the scientific progress made of radiation that is as narrow as tributions from all slots. Due to by using this machine. In the ac- possible, without so-called “side interference, the fields generat- companying survey article [2] lobes” (figure 2). Since the radi- ed by the individual slots amplify more details of the machine are ation pattern of a single antenna each other in the antenna aiming presented. After studying these is relatively wide, an array of an- direction and weaken each other articles and opening up the ma- tenna-slots is used to achieve a in the other directions, thereby chine to examine its construc- narrow beam (figure 3). The total reducing the effect of the side tion, gradually, a picture began field generated by these anten- lobes. to emerge of the purpose and na-slots is the sum of the con- Antenna aiming direction Main Lobe Side Lobe Side Lobe Side Lobe Side Lobe Fig 2. Radiation Diagram of a single Fig 3. Example of a slotted antenna antenna 6 March 2021
24.2 The Design of the Computer slots. In other words, this unique a signal distribution device These Hammer’s computer is designed mechanical / analogue machine channels are numbered -20° .. 0° to perform two functions: (i) using simulates radar waves. The .. +20°. Each channel simulates up to 41 antenna slots, the machine block diagram of the computer one antenna slot. calculates the field strength can be seen in figure 4. Whereas of the E-field, and (ii) starting the frequency range of radar is from a prescribed radiation around 30 GHz, here a frequency pattern, the machine calculates of 1000 Hz is used. The sine wave the needed contributions of the of 1000 Hz is presented to 41 (at most 41) individual antenna parallel calculation channels via Fig 4. The block diagram of Hammer’s machine. All calculations assume that the antenna slots are the same distance ‘d’ from each other Fig 5. X-Y resolvers and the gear box. The positive resolvers rotate clockwise; the negative counter clockwise. The central resolver is stationary March 2021 7
24.2 To calculate the E-field the oper- gearbox is driven by a central cessing. Towards this purpose, a ator manually sets the amplitude motor. This motor sets the angle so-called ‘rootpot’ is connected and phase of each antenna slot θ from the aiming direction. to the circuit [2]. The functioning on the computer. The amplitude Using the formula of this part is based on finding for each channel can be set with the roots of the equation a buffered 10-turn helipot. Some more thought was put into setting the phase on this ma- the strength of the E-field of the chine. Each channel is equipped nth antenna slot is calculated. Solving this equation using the with a so-called x-y resolver. The Subsequently, all field strengths ‘rootpot’ will give a number of experimenter sets the desired are added together: complex roots. Although this part value of the phase by manually has been located in the machin- turning the stator of the resolv- ery (figure 7), its precise opera- er. The rotor of each resolver is tion is still unclear. Presumably driven from a central gearbox The result is shown to the exper- the ‘rootpot’ is also used as the with ratios 1: 2: 3: ..: 20. When the imenter via an oscilloscope and/ aforementioned signal distribu- desired phase is set, the x-y re- or a paper recording device (re- tion device. solver translates the mechani- member when paper recording cal angle between the stator and was a norm?) as shown in fig- Hammer’s computer calculates the rotor into two AC voltages ure 1. The addition of the signals the E-field in 12 seconds. Digital [5]. Both, the resolvers and the is done via buffered amplifiers computers of that time (in 1955) gearbox, have been mounted on that use vacuum tubes. Figure needed 700 seconds for this cal- a very sturdy sub-chassis, so 6 shows the bottom part of the culation. The great developments as to increase the accuracy of electronic signal processing unit that took place in digital tech- the computation. Figure 5 shows of eight resolvers. nology later made this analogue some resolvers and the gearbox. / mechanical calculator from The computer’s second function Hammer superfluous, and it was The E- field is calculated for a of is calculating the amplitude eventually donated to the Study large number of angles and phase settings of the anten- Collection in Delft. (θ = -30° , ... , + 30°) from the na slots starting with the pre- antenna aiming direction). The scribed E-field i.e. inverse pro- Fig 6. Electronics for signal Fig 7. The Rootpot processing of 8 resolvers 8 March 2021
24.2 Applications of Linear Radar used here. For more information ed scientific and applied work on Antennas on modern techniques, the read- this subject. One of the develop- Various radar installations were er is referred to [4]. ments was the creation of this constructed on the basis of ex- analogue / mechanical computer periments with Hammer’s com- Conclusion by ir. J. A. Hammer in the years puter, both onshore and on frig- During the Second World War, the 1950-1955. It is remarkable that ates of the Royal Dutch Navy. development of radar technology Dutch engineers were able to Figure 8 shows an application in the Netherlands came almost create this splendid example of of a linear radar antenna on the to a standstill. After the war electronic and mechanical design Dutch frigate zr. ms. Tromp (the was done, it was decided that so shortly after the end of WWII. black box on the stern, designed the Netherlands should start its and produced by Thales in Hen- own developments in this field. gelo). Of course, the most mod- The Dutch Radar Test Station was ern radar techniques have been established in 1947, and it start- Fig 8. zr. ms Tromp Literature: [1]The Evaluation of Diffraction Prob- thesis of Linear Arrays with Prescribed [4]https://www.museumwaalsdorp.nl/nl/ lems in Aerial Technology by Means of an Radiation radar-nl/radar-phased-array-onderzo- Analyser for Patterns: A Survey of some Early Work ek/ Complex and Fourier Series, by: J. A. at the Christiaan Huygens Laboratory, by: Hammer in: Principes fondamentaux: E. Goldbohm (formerly professor at [5]X-Yresolver: https://en.wikipedia.org/ Équations de Maxwell, Principe de Huy- TUDelft) in: IEEE Antennas and Propaga- wiki/Resolver_(electrical) gens et Théorie de la diffraction en hyper- tion Magazine, Vol. 35 No. 3, June 1993 tennas and Propagation Magazine, Vol. 35 fréquences (1956) No. 3, June 1993 [ 3 ] h t t p s : / / w w w.c r y p t o m u s eu m .c o m / [2]Near Field Measurements and the Syn- manuf/nrp/files/nrp_40.pdf March 2021 9
24.2 EV Charging: Load Prediction, Smart Charging and its Impact on the Electric Grid Interview with Dr.ir. G.R. Chandra Mouli Aniruddh Kulkarni Dr. G.R. Chandra Mouli is an As- face of the automobile market: sistant Professor in the DC sys- the electric vehicles. In 2010, the tems, Energy conversion and global count of electric cars was Storage group in the Department only 17,000. As per the Interna- of Electrical Sustainable Energy. tional Energy Agency, the auto- He has received his PhD from mobile market has seen a year- the Delft University in 2018 on on-year growth of 6%, swelling the dissertation associated to the total count of electric cars to the development of a solar pow- 7.2 million1. ered V2G electric vehicle charg- er compatible with CHAdeMO, This exponential rise in the num- CCS/COMBO and designed smart ber of electric vehicles, raises an charging algorithms. Dr. G.R. important question: Is the charg- Chandra Mouli received ‘Under 35 ing infrastructure developing at Innovator’ award from the IEEE par with the vehicle technology? Industrial Electronic Society in To this Dr. G.R. Chandra Mou- 2019. Based on the specialization li puts forth a perspective that of Dr. G.R. Chandra Mouli, we dis- this development of charging in- ance is maintained in the ratio of cuss the future of the electric ve- frastructure is dependent on the number of vehicles to the charg- hicle charging infrastructure. The country. Development of charging ing stations. This development in 21st century has seen the new infrastructure means that, a bal- the charging infrastructure var- Fig-1: Rise of EV market from 2010 to 2019 10 March 2021
24.2 ies by geography. According to in installing and operating charg- tering to the peak demand of the International Energy Agency, ing stations are Fastned, Ionity, the load. The peak demand cy- the global figure for installed Tesla Supercharger, EVgo. cle occurs at fixed durations chargers were 7.3 million in 2021. in a 24-hour cycle. Congestion There are a few countries which The load experienced due to Management deals with spread- have more vehicles than the charging EV’s has much higher ing out the time during the peak charging infrastructure. Figure-2 magnitude than the conventional load hours throughout the 24- shows country-wise distribution loads. Hence, the impact on the hour period such that the energy of number of charging stations electrical grid will be much high- consumed remains the same but built. This imbalance results in er when the EV-charging is taken the power reduces for the peak Publicly accessible slow chargers 598,000 Publicly accessible fast chargers 264,000 Fig-2: Global distribution of publicly available charging stations Publicly accessible fast chargers 264,000 an increased waiting time for us- into account. Most of the pres- load time intervals. An alter- ers to charge their vehicles or to ent distribution electrical grids nate method is to install locally commute to large distances due are not capable of handling such generated renewable charging to unavailability of nearby charg- kinds of loads. For reducing this stations. This will be effective in ing stations. impact on the grid techniques like sense that there will be less im- “Smart Charging” have come to pact of the load on the grid. The charging infrastructure can existence. Smart charging aims Aggregator based Charging: - be categorized into two types: at managing the supply and de- One of techniques of smart The first type of charging sta- mand of the EV charging, by es- charging is the aggregator-based tion is a long duration charging tablishing protocols/algorithms charging. Aggregator based station i.e., chargers located in to the way the users charge their charging is one of the techniques offices, public charging stations vehicle and control the way in which involves the contribution within the city etc. Such sta- which battery of an electric ve- of the whole EV ecosystem. The tions are meant for fulfilling the hicle is charged/discharged. This EV (electric vehicle) ecosystem daily charging requirements of is one of the focus points of the consists of several key compo- EV owners. The second type of Department of Electrical and nents: the car manufacturers, charging stations are meant for Sustainable Energy. One of the the charger manufacturing in- fast charging. These stations are techniques that Dr. G.R. Chan- dustries, industries that install located on highways and routes dra Mouli confers is Congestion and operate the chargers, indi- of long-distance travel. Some of Management. This in other words vidual entities that provide the the industries making progress is the efficient management ca- charge controlling software. The March 2021 11
24.2 energy market players such as demand of every individual EV not included in the aggregator energy producers and suppliers, user. This charging information supervision. The load at such companies responsible for sup- is dependent on the user profile charging stations can be ac- ply-demand balance and the dis- by collecting information such counted for as uncertain load. tribution system operators also a as arrival time, parking time. Out Hence, the net load predic- part of the EV ecosystem. of the whole EV ecosystem, any tion is made by observing the An individual EV owner/user does entity can take up the role of an charging pattern of EV owners Traditional wide beam communication systems vs next generation system with dedicated for users not have any idea of the total load aggregator. Independent entities and extrapolating the data. experienced by the grid at certain can also assume the role of an The load due to EV charging is point of time. Hence, from a cus- aggregator. Multiple aggregator a long duration load imposed tomer centric view the control of companies are present in the on the grid as compared to the charging is not possible. Based ecosystem which collect the data conventional loads, which are on the user behaviour, of a set of users for predicting switched frequently. Due to the there are certain durations in a and controlling a part of the load. prolonged time for charging, day in which most of the EV’s of Collectively, this data presents there will be an overlapping in a particular region will be charg- the total load profile at a national the loading conditions i.e., due ing. This will result into a surge grid level. to multiple users charging their of the load on the grid. These in- vehicles in the same time dura- termittent surges of load during To acquire the data of individual tion. Once the load profile is built the peak demand duration have charging demand, the aggrega- based on integrating individual to be distributed in order to re- tors use different charging pro- charging demand, in the same duce adverse impact on the grid. tocols. Some of the charging pro- time duration. Based on the grid To accomplish this distribution tocols used by the aggregators congestion and available sourc- there will be some potential en- are Open Charge Point protocol, es such as renewable charging, tities in the future, who will be the Open Smart Charging proto- different pricing schemes can be responsible to cluster the data col. For example, the e-mobility devised. The cost for charging is and provide a prediction of load, service provider handles the fi- determined based on the optimal spread out in a 24-hour cycle. nancial transactions related to power consumed versus time These entities are called “Aggre- charging. This financial trans- profile for every individual vehi- gators.” action reflects the details com- cle. Hence, one of the possible prising of duration of charging, methods is to decrease the load- The primary function of an aggre- location of charging etc. Howev- ing during peak demand is to in- gator is to acquire the charging er, some charging stations are crease the price charged per unit 12 March 2021
24.2 power consumed (cost/kWh). mand [2]. This data concerns with installed capacity. the grid loading conditions. For an The above situation describes Despite the smart charging tech- individual, the maximum demand that the grid will certainly need niques, there are multiple factors will increase by 18% from every an upgrade in the power capacity determining the loading on the 10% increase in houses with EV’s to satisfy the growing demand of grid such as EV penetration, grid [3]. The impact of this increased EV charging. However, upgrading features, rated charging power of load will be more prominent on the grid will require a significant vehicles, charging behaviour pat- the distribution network than the investment. Hence, Dr. G.R. Chan- tern etc. Based on the EV pene- transmission network. Most of dra Mouli believes that the future tration the peak load for grid has the distribution network have an of charging infrastructure will been calculated. Research has installed capacity to operate at turn towards an optimal solu- shown that a 10% market pene- higher load conditions, there are tion which combines the smart tration of EV would result in an some networks present which charging techniques and the up- increase of 17.9% in daily peak operate near to the peak load. grade in electrical gird. demand while a 20% market pen- Such networks, will undergo etration would result in an in- overloading condition. This issue crease of 35.8% in daily peak de- can be resolved by increasing the References: - 1. IEA (2020), Global EV Outlook 2020, IEA, vol. 26, no. 2, pp. 802-810, May 2011, doi: Dearborn, MI, USA, 2009, pp. 827-831, doi: Paris https://www.iea.org/reports/global- 10.1109/TPWRS.2010.2057456. 10.1109/VPPC.2009.5289760. ev-outlook-2020 3. G. A. Putrus, P. Suwanapingkarl, D. 2. K. Qian, C. Zhou, M. Allan and Y. Yuan, Johnston, E. C. Bentley and M. Narayana, “Modeling of Load Demand Due to EV “Impact of electric vehicles on power Battery Charging in Distribution Systems,” distribution networks,” 2009 IEEE Vehicle in IEEE Transactions on Power Systems, Power and Propulsion Conference, March 2021 13
24.2 Black Hole Visualization Annemieke Verbraeck A surprising amount of black- hole articles It seems every week I find a new article on my feed concerning new and surprising discover- ies in space. Many of these are about black holes, although that might be just me, as Google must think I am obsessed with the phenomenon after searching for the Black Hole Wikipedia article hundreds of times during my re- search. Even though black holes are surprisingly simple - some of them can be defined with only one parameter – their influence on their surroundings is not easy to grasp. Despite my background in Astronomy, I often found my- self double checking the basics to make sure my implementa- tions and definitions were cor- rect. If my Astronomy BSc taught me anything, it is how easy it is to make mistakes dealing with Copyright© Frank Auperlé complicated physics formulas that cannot be verified in an ex- visualization, and concluded that periment on earth. their simulation was not optimal, Taking a trip to a black hole at least in terms of speed. With The easiest is to start the expla- From Astronomy to Computer my astronomy background, I was nation of our research with a little Graphics the perfect candidate to fully un- thought experiment to describe Another thing the Astronomy BSc derstand all the formulas in the our setting. Imagine yourself to taught me, is that those physics paper and work out a smarter be a wealthy tourist on one of the formulas were a bit too abstract and faster solutiovn. I am now in first spaceship trips. The guide for me and a lot more present in my third year of my PhD at the starts talking excitedly, as you the study than the pretty Hubble Computer Graphics group, and are approaching the grand fina- Telescope imaging of deep space. only this October did we publish le of the tour, a real Kerr black This realization led me to pursue a a paper on our findings. As it of- hole. Unlike Schwarzschild black master in computer science with ten goes in research, at first it is holes, Kerr black holes are spin- a specialization in Graphics at more difficult than expected and ning rapidly, so the spaceship the TU Delft. For my masters pro- at the end there is always some has entered a stable orbit around ject, the professor of our group, code to improve and some func- it, to prevent getting sucked in. Elmar Eisemann, immediately tionality to add. The end result After all this travelling you know knew what I was going to spent was worth all the work howev- that space is a very empty place, all my time on. He saw the mov- er as we received an honorable so while you are close to the black ie Interstellar, skimmed through mention for best SciVis paper at hole, all the stars and galaxies the paper about their black hole the Vis 2020 conference. are almost infinitely far away. So 14 March 2021
24.2 far away in fact that if you would fore we can go on touristic trips curved paths through space. As make a simulation, they could to a black hole, so until then we we only detect the photons when be approximated by existing on have to be satisfied with simula- they reach our eyes, we expect a celestial sphere with infinite tions, but not everyone has a CPU the star to be located in the di- radius around you and the black farm at their disposal. Our ap- rection where the photon arrived hole. The big question now is of proach therefore aims to produce from. On top of that you can see course, what do you see when a high-quality interactive simula- that different light rays from one you look out the window? What tion that can be run on your own star follow different paths to your do you expect to see? computer in real time, to come a eye, which means photons from little closer to that experience of the ame star come in at different Real image versus Simulation looking out of the window of the angles, and thus show you im- The first thing that now pops spaceship. ages of the same star at differ- into your mind is probably the ent locations in Fig.2. To make it image of our simulation (Fig.1) I will explain step by step how even more crazy, the multiplying that made you interested in this we achieve this, but before that, effect happens an infinite num- article in the first place. Had you we first must understand why ber of times. And then some light not seen it however, it might be visualizing a black hole is not rays do not reach your eye at all, the image of an existing black straightforward and why it took as they are trapped by the black hole that was constructed last Interstellar so long to render hole and cannot escape. This re- Fig 1: Result of the simulation year from telescopic data, or it these frames. sults in the black portion in im- might be a simulation, like the agery of black holes, called the one of Gargantua, the black hole Infinite Images shadow. Looking at it from this in Interstellar. A large team of As mentioned before, black holes way, saying that we aim to visu- researchers worked on its de- influence their surroundings. The alize a black hole is not accurate piction - one of which is the fa- presence of a massive body like at all, as the only thing we see – mous astrophysicist Kip Thorne a black hole deforms space-time, or not see – is how it influences - to make sure it was a very and this affects everything that space around it. precise and physically accurate gets close to it, even weightless simulation. While this research particles like photons. Let us Light always takes the shortest produced IMAX quality imagery, imagine following the light rays path a CPU farm was required for ren- originating from a far-away star Making a virtual world and de- dering, and for some frames this until they hit your eye. As you can picting it as accurately as possi- process took up to 100 hours. see in Fig.3, due to the presence ble on a computer screen is what of the black hole, the rays do not computer graphics research is Obviously it will take a while be- follow straight lines, but take for. The most basic approach March 2021 15
24.2 uses the physical principle that interactive simulation is not fea- and brightness. The elliptical we can observe an object be- sible when having to trace lots of ray bundle equations are even cause there is light that hits the these rays. This means there are more complicated than single object, and then bounces from two things we had to do: making rays however, and thus take the object into our eyes, enabling the ray tracing faster, and doing even longer to compute. us to construct an image of it in less of it. our mind. We invert this princi- Step 1: Faster Raytracing ple to get images from a virtual Our first step to achieve Fig 2: Due to the presence of the black hole, we see Fig 3: Light rays will always follow the shortest path multiple versions of the same star at different locations. from A to B. world onto a screen. To find out Stellar Problem speedup is to use the principle the correct color for each pixel The researchers depicting the behind the complicated ellipti- we trace a light ray back from the stellar sky behind Gargantua cal bundles, but do the actual viewer, through the pixel, into the quickly found out that their initial tracing using single rays. We virtual scene, to see what object method of tracing one or multi- also work with an area, but it hits and if the object is illumi- ple rays per pixel resulted in a one that starts as a square, the nated. However, these scenes completely black image. The rea- pixel itself. We then trace a ray are usually in an earth-like en- son for this is that the stars are through every pixel corner and vironment, where light rays fol- defined as point lights and hitting end up with a polygonal region low straight lines, and we can in this exact point with a traced ray on the celestial sky, which we general expect objects to be lo- is almost impossible. While larg- can integrate just like the el- cated at the direction we observe er objects like galaxies can be liptical area. As every corner them in. For our black hole case, projected onto a 360-panorama is shared by 4 pixels, we get we do take a similar approach, map that covers the celestial sky to trace an area at the cost of where we start at the viewer and (Fig.5), stars are much smaller only one ray per pixel. With our trace rays through the pixel back lights than even one pixel. The polygonal regions we trade in a to the Celestial Sky to see what solution for their missing stars bit of quality for a lot of speed- star or galaxy it hits there. Due was not to trace single rays, but up. to the presence of the black hole elliptical ray bundles. Every bun- however, this ray will be curved, dle starts from a spherical area In practice the integration and can only be traced through around a pixel, gets traced back at the celestial sky is noth- space by performing a numerical through space and ends up as ing more than a check to see integration of a set of differential an elliptical area on the celes- which stars and which part of equations based on the space- tial sky (Fig.4). All stars in this the 360 panorama is included time metric. This ray-tracing in- area could then be integrated to in the polygon, and then adding tegration is very costly, and an determine the final pixel color up their colors and brightness. 16 March 2021
24.2 Step 2: Less Raytracing the edge of the black-hole shad- need to find the mapping from For the second step of our speed- ow. A lot of rays are needed in every pixel corner to its loca- up, we use the fact that the dis- those regions to correctly inter- tion on the celestial sky. With tortion of the environment stays polate, but in less distorted re- an adaptive grid, we have the the same as long as we stay in the gions, we can probably get away mapping for each grid vertex to same place. For one such posi- with much less. To decrease the the celestial-sky location. Sub- tion, we only compute rays once, number of rays even further, we sequently, we have to locate in coming in from directions defined construct an adaptive grid that which grid cell a pixel corner is on a spherical grid all around us. refines more in areas with more located, and then interpolate the Because the distortion is smooth, distortion. To construct the grid, surrounding values of the grid we can interpolate this generat- we start with large grid cells and to find the pixel corner’s celes- ed grid to create images looking use the amount of distortion to tial-sky location. To better ap- in any orientation and with differ- check if they need to be divided. proximate the smoothness of the ent projections. This way, we can The end result can be seen in distortion and avoid artefacts, we Fig4: Top: Elliptical ray bundles by Interstellar, Bottom: Our polygonal ray bundles made out of single rays. Fig 5: Left: Celestial sky map, Middle: Map as a panorama image, Right: Distortion of celestial sky by a black hole, seen in panorama view show what our eyes would see Fig.6. Depending on the position use Hermite Splines for our in- with their limited field of view, or of the viewer, the adaptive grid terpolation method. show how everything around us traces around 40 times less rays deforms at once, with a 360 pan- than the standard one. What about our trip around the orama like in Fig.1. black hole? As you can see in Fig.5, the dis- Interpolation Now we can compute grids, but tortion is more severe closer to When constructing an image, we unfortunately even with all im- March 2021 17
24.2 provements it takes about half a into too much detail here, our Looking back in time second for all rays to be traced, solution computes the interpo- When we observe space, we are so too long for interactive fram- lated shadow and warps the two looking back in time, as it takes erates. Luckily when we have the existing grids around it – mak- quite a while for light from distant grids, we can render the images ing it possible to interpolate the stars and galaxies to reach us. As Fig 6: Adaptive grid in panorama view. Every intersection on this grid represents a light ray that has been traced back to the celestial sky. in real-time, by performing this grids at the same positions. I am very busy with a new project, step in parallel on the GPU. Our the black-hole simulation already mission was however, to be able And of course, a lot more starts feeling like a thing from the to feel like we are in a spaceship, This is not all functionality our past. It would be great however, to travelling around the black hole. method has, but it does outline bring this software to an educa- If for every position our space- the largest steps that enabled us tional space. I would have enjoyed ship is at, we have to wait half a to make a high-quality interactive some of my astronomy lectures second for a new grid, our imple- simulation, while tracing only a a lot more if the professors had mentation would not be very in- fraction of rays compared to pre- shown me simulations like this! teractive. To solve this, we come vious solutions. We also made to our last attempt at simplifi- sure to emphasize the aesthet- Podcast episode with Annemieke Verbraeck cation and decreasing compute ics of the resulting imagery, we In The ProfCast, Marieke (PhD candidate time; we aim to compute less are from the Computer Graphics Applied Mathematics) and Dave (communi- grids. group after all! For stars we use a cations advisor) talk to scientists who want Gaussian filter to show their dif- to improve the world, who prefer to educate Step 2.5: Less grids ference in brightness and added young people and who avre looking for that To simulate movement, without diffraction effects (Fig.8). While one spark. What drives them? Where does having to recompute the grid the particular pattern we use is their fascination with science come from? all the time, we came up with a an artifact caused by the vanes And how do they dealv with all the hus- method to interpolate between of a telescope, we are so used tle and bustle? In recent weeks they spoke grids at different positions. This to see imagery of space like this, with Annemieke Verbraeck, among others. is not as simple as it seems, if we that it was a natural addition. We Black holes are one of the most remark- look at the deformations between also include color and brightness able phenomena in the universe. But what two grids, like in Fig.7, it is clear changes induced by the black do they look like? And how do you represent that one produces a larger shad- hole, as it influences the wave- such a thing? Researcher Annemieke Ver- ow. If we would just lay them on length of photons passing by and braeck developed a new simulation based top of each other and interpolate, creates other fascinating effects on the Hollywood film Interstellar. Professor there is a region in which one (Fig.9). Elmar Eisemann and Professor Alexander grid does not have any informa- Verbraeck also speak in this episode. tion to contribute. Without going 18 March 2021
24.2 Fig 7: Interpolation between grids A and B to find grid I. The grids are warped around the interpolated shadow to make interpolation possible. Fig 8: Star effects, from left to right: No effect, Gaussian filter, Trails to make movement go smooth between frames, diffraction, the image used to make the diffraction. Fig 9: Effects on brightness and color: From top to bottom: No effects, Redshift effect, Lensing effect. March 2021 19
24.2 A Physicist who never lost her humanity Aniruddh Kulkarni The epitaph “A physicist who never lost her humanity” is attributed to the respected human being and great physicist Lise Meitner. In the year 1945, Otto Hahn received the Nobel Prize in Chemistry for the discovery of nuclear fission. However, Lise Meitner despite of being associated with the project for the whole of her lifetime, unfortunately did not receive the honor to be the recipient of the Nobel prize. Lise Meitner was born in a Jewish to the field of study still prevailed. collaboration of Lise Meitner and family on November 7th, 1878 in Owing to these restrictions, Lise Otto Hahn started with research Vienna, Austria. The primary ed- could only enter the University on Beta emission. Their collabo- ucation in Austria had been man- of Vienna in the year 1901. With ration prevailed for 30 years, in dated by Empress Maria Theresa Ludwig Boltzmann as her men- which they worked on radioactive in 1775. Till the 1800’s the reason tor, she entered the world of substances and conducted ex- that women are not competent physics. Otto Robert Frisch once periments for obtaining isotopes enough was used as an argument said that Lise Meitner made her of different elements. The results to restrict women from entering vision of physics as battle for the of their work were published in universities. Starting from the ultimate truth, a vision that she three major articles in the year year 1872, women were allowed never lost. Following her doctor- 1908. The World war I started in to graduate yet they remained ate, she moved to Berlin in 1907, 1914 and during this period Hahn excluded from some specific uni- where she attended lectures served in the German gas ser- versities due to the ideology. By by Max Planck. At University of vice headed by Haber, while Lise the year 1901, this ideology was Berlin, Lise Meitner started her served as X-ray nurse for the discarded and women were al- research with radioactive sub- Austrian army. In 1917, they iso- lowed to enter universities how- stances along with Otto Hahn. lated the isotope of the element ever some restrictions pertaining The beginning of the long-lasting protactinium. In 1932, James 20 March 2020
24.2 Chadwick presented a conclu- holm where she took up a post an immense amount of energy is sive proof on the existence of at Manne Siegbahn’s laboratory. released during the fission re- neutrons. This proved to be as a This was the place where she action, the idea of using nuclear stimulus to the research of Lise collaborated with the noted sci- fission reaction as a potential Meitner and Otto Hahn which in- entist Niels Bohr. However, Lise weapon emerged. The methodol- vestigation of the effects on neu- and Otto Hahn remained in touch ogy of how an atomic explosion tron bombardment of nuclei. during that time. In December, would take place, published by Otto Hahn and Fritz Strassman Frisch-Peierls, became the ba- In 1934 Ernico Fermi experiment- conducted experiments which sis of the establishment of the ed with the effects of bombarding was on the process of ‘bursting Manhattan Project. Lise Meitner neutrons on elements for pro- of uranium’ which later came to however turned down the offer ducing isotopes. The bombard- be known as the nuclear fission declaring, “I will have nothing to ment of neutrons of elements reaction. However, the results of do with a bomb!” yielded isotopes of the element. the experiments turned out to be However, one anomaly emerged unusual. Lise and Frisch articu- Lise Meitner contributed to the during this research, which was lated the results using the “liquid foundation of the nuclear fission the behaviour of element urani- drop model” of the nucleus, that reaction. Between 1924 to 1938, um. Upon bombarding neutrons the uranium nuclei split into el- Lise Meitner and Otto Hahn were on uranium there were several ements Barium and Krypton. The nominated for the Nobel Prize products produced as opposed term nuclear fission was first 19 times, 17 times for the field of to the definitive results yielded coined by Otto Frisch which ex- chemistry and 2 times for physics. by other elements. This behav- plained the ‘bursting of uranium’ However, due to the Lise’s emi- iour could not be explained. This and resulting release of an im- gration and intermittent collabo- puzzle only grew by the year 1938 mense amount of energy. This re- ration with Otto Hahn, the Nobel which was a pivotal year for the sult provided a conclusive proof committee did not consider the scientific community in Austria, that all the elements beyond ura- contribution made by Lise. This and shortly before World War II. nium in the periodic table could resulted in Otto Hahn winning not exist in a stable state. The the Nobel prize. This mistake by In 1938, the annexation of Austria results of the experiment were the Nobel committee was partly into Germany took place which is presented in Naturwissenschaf- rectified when Lise Meitner, Otto referred to as the “Anschluss.” ten in 1939. Hahn and Fritz Strassman were During this political union, many awarded the U.S. Fermi Prize. scientists were dismissed or The explanation of the empiri- The element “Meitnerium (Atomic forced to resign. This became a cal results provided by Lise and Number 109)” has been named in reason for many renowned scien- Frisch had a scintillating impact the honor of Lise Meitner. tists to emigrate, Lise being one on the scientific community. Once of them. Lise moved to Stock- there was conclusive proof that March 2020 21
24.2 Master Student Column Internship at SLAM Ortho Jan de Jong Jan is now a second-year master moving to Rotterdam and starting student in Computer Engineering. my thesis soon, so it’s kind of the He started his bachelor’s in elec- end of an era. trical engineering 8 years ago still open, but that’s for another right here in Delft, during which What do you like to do in your time maybe. time he was also active in ETV. free time? I’ve always been interested in What was your motivation for Tell us something about your- technical stuff since I was a doing an internship? self! child - being into LEGOs, building During the first year of my mas- It has been some years since I things with my sisters and stuff. I ter, it was quite hard to find any have been an active member of really like the technical aspect of interesting courses in the first this association. So, a brief intro- electrical and mechanical stuff, quarter of the first semester. duction. I did a lot at the ETV, as but also actually building things Therefore, I decided quite early well as a board year in my third and working with my hands. I’m on in the year that I wanted to do year. During my year we also had very happy I could make it come something other than CE cours- the Lustrum year, so there were together into a study. I also liked es for my free elective space. a lot of festivities going on. This swimming, and now I’ve picked And, quite thankfully, this op- year I am still doing the Board of it up again. And of course, be- portunity was presented to me Studies in Computer Engineering, ing with friends. It was always a during spring/summer: I was ap- so I’m still a bit involved, but I’m good time at the pub when it was proached by a friend who works 22 March 2021
24.2 at the company SLAM Orthope- domains of electrical, mechan- dics, to see if I was interested in ical and computer engineering. doing an internship with them. But I didn’t really have experi- ence in building a PCB etc, so SLAM Ortho is a startup with its that was all new for me. I had to offices at the YES!Delft incubator learn Fusion360, which is a pro- on the TU Delft campus. They fo- gram by Autodesk that you can cus on surgical orthopedic drill- use for fast prototyping for 3D . ing, and are developing an adapt- I learnt to actually make a board, er add-on for a surgical drill that although it wasn’t a very hard can automatically measure the board to make, but it had a good drill depth in bones. This is used number of electrical components in plate osteosynthesis wherein a for a first board. There were also metal plate is fixated to the bones some challenges, and debugging to stabilize a bone fracture. Their is also a really important skill - product drastically shortens the very frustrating, but it can also operation procedure and will be rewarding. There was a lot of also cause the procedure to be software writing, and although I ciety can be made in the case of less error prone since the meas- am a computer engineering stu- SLAM Ortho. urement step is automated. dent, this is one of my least fa- vourite things. Do you have any advice for cur- Tell us a bit about your intern- rent students? ship assignment. It was a really friendly environ- I would recommend everyone to My internship assignment was to ment. I would like to see that in a do an internship in their master design and prototype a portable company when I apply for a real programme. It is very interesting receiver for the sensor adapter job. If you want to really work in a how you can apply the knowledge that they are currently develop- team and get the best out of each from courses in such an assign- ing. They had to show it to their other, you need to know each ment. You learn the translational clients and convince them to buy other - but that’s also one of the step between all the theory, and it, so it had to be awesome. The things I’ve learned from my board its practical implementation and whole design loop was walked year. prototyping. Besides this, it also through and everything, from re- gives a good perspective on the search into requirements to the What was your favourite part dynamics in a company and how final assembly, was touched. One about the experience? they differ from academia, so you of the most exciting things in my It was an amazing experience, don’t end up going to work and experience was designing and and one of the things I would nev- not know what ‘working’ is, be- producing a custom SMD PCB. er forget would be the ambience cause you’re in for a treat then. There is no such opportunity within a startup. The amount of elsewhere in the CE study pro- freedom that is available to you With all of this being said, I’m gram. is also quite a large responsibil- very thankful for the opportuni- ity. I learnt a lot about the design ty I’ve gotten from SLAM Ortho Within a quarter it was possible cycle, without everything being and the TU Delft. I will soon begin to do all of these things, and in defined for you in an assignment on my master thesis project and the end, a proof of concept for by the TU. But because of that will proceed to conclude my time the portable receiver was deliv- you can let your creativity thrive. here in Delft. And I hope you will ered. For SLAM Ortho this meant And thus, you can really stay on all consider an internship as a that a lot of new information was top of next-generation ideas. I part of your master programme. gained, and further strategies now really know what it is like to could be researched. actually design electronics for a company. Did you feel prepared for it? I already enjoy building stuff, Besides this awesome ambience, and also connecting the three a very useful contribution to so- March 2021 23
24.2 Bachelor Student Column Gijs Lagerweij, Third Year Electrical Engineering Gijs is a third-year Bachelor stu- it was close to where I live. ly involves theoretical elements dent electrical engineering at the such as a literature study and TU Delft. He has done an intern- Why did you choose to do an modelling, as well as practical ship at Prodrive Technologies for internship for your minor? elements such as design, test- his minor. There are two reasons for that. ing, performing measurements, Firstly, the TU Delft did not of- and analyzing the obtained data. Why did you choose Electrical fer many minors in areas that Another very important aspect Engineering at the TU Delft? interested me. Secondly, I want- is documentation, which should To me Electrical Engineering ed to apply the knowledge and help your colleagues understand was, and still is, a very interest- skills that I have acquired over the outcomes of your project af- ing and broad discipline with ap- the years. (Work) experience is ter it is finished. plications in almost every aspect something that goes beyond what of our lives. I knew pretty early you learn at university, which is Where did you do your intern- on that I wanted to do Electrical mostly theoretical. An internship ship? Engineering. It was a combina- helps you develop practical abil- I did my internship at Prodrive tion of the courses I liked during ities, which is very valuable for Technologies located in Eind- high school, as well as my hob- your development as an engineer. hoven. Prodrive is a technology bies. My father, who is also an company comprising over 1300 electrical engineer, was always Do you think there is a large employees and is one of the fast- happy to help or explain things. difference between studying est-growing companies in Eu- His support certainly gave me a and doing an internship? rope. Prodrive designs and man- nudge in the right direction. Definitely. The goal of most cours- ufactures electronics, software, I chose to pursue this course of es at university is to give you a and mechanics, power electron- studies at the TU Delft because I broad theoretical understanding ics being the core competence, liked this university best. I also of various concepts that belong and is active in many different visited several other universities, to that subject, this is tested at an industries, such as the medical, but Delft felt like the right choice exam. During an internship, there industrial, automotive and sem- to me, both in terms of atmos- is no exam, instead, your goal iconductor industries. Their ca- phere and in terms of the aca- is to complete the project that pabilities include in-house pro- demic environment. Additionally, is assigned to you. This typical- duction, assembly, testing and 24 March 2021
24.2 life-cycle-management of elec- had to be analyzed, after which Did the coronavirus have an tronic products and systems. I had to make a comparison be- impact on your work? tween the variants. A number Of course, but it was not as bad Can you tell us more about of custom power modules with as it could have been. Working your project at Prodrive? integrated passives were also from home is unavoidable these Within Prodrive, numerous prod- compared against discrete SiC days, but thankfully Prodrive re- ucts incorporate power modules MOSFETs in identical configura- sponded very well to the virus. and discrete semiconductor de- tions. They implemented strict rules vices. These parts are off-the- The results of this investiga- which allowed location critical shelf products which are typi- tion were quite promising. We work (e.g., lab and production cally not optimized for electrical observed an improvement of work) to continue in a certain ca- and thermal performance in the roughly 25% to 50% in steady- pacity. These rules allowed me specific application. This is es- state thermal performance over to spend a significant amount of pecially the case for higher-per- the operating range when com- time on-site. Aside from some formance WBG devices. Prodrive paring the custom power mod- minor delays for ordering PCBs, is now developing custom pow- ules to the discrete SiC MOSFET components, etc., there was no er modules using SiC MOSFETs solution. By integrating decou- significant impact on my project. in an effort to drive down con- pling and snubber into the mod- verter costs and improve per- ule, we were able to achieve 75% What did you like the most about formance. These power modules lower undershoot and oscillation doing an internship? provide a larger degree of flex- than with the decoupling outside I really liked that I was able to ibility in high-efficiency power the module. completely focus on a subject conversion products. One way of We have also identified some that interests me. The internship optimizing the electrical perfor- limitations of the modules and gave me the time required to dive mance is through the integration potential paths for improvement. into the subject and create some of various components (snubber, The general expectation is that, good, useful results. Usually, you decoupling, gate driver, etc.) into with the power semiconductor do not get this amount of time at the module. technology shifting from Si to SiC university, where you touch upon The goal of my project was to and GaN, the ‘vertical integration’ many parts of a subject, but never completely characterize and ver- in terms of packaging will be- really dive deep into the details, ify the electrical and thermal be- come more and more important at least during the Bachelor. haviour of various custom power for the company to be able to de- At the same time, I also enjoyed module configurations incorpo- sign power conversion products the cooperation between disci- rating passive components. The with high reliability, long lifetime plines. It seems every discipline assignment involved qualification and low cost/performance ratio. has its own perspective and of a test setup specifically devel- working together can give rise to oped to be able to characterize How did you experience the at- interesting discussions and new both the hard and soft-switching mosphere at Prodrive? insight. performance of any half-bridge, The atmosphere at Prodrive was both discrete MOSFETs as well very pleasant. It is quite informal, as (custom) power modules, de- and you can talk to anyone at any velopment of a measurement time. My colleagues were happy procedure, as well as conducting to help and explain anything dur- the measurements. The electrical ing my internship, either in the and thermal performance then office or through a Teams call. March 2021 25
24.2 What is Quantum Computing? Prof.dr.ir. K.L.M. Bertels Prof. Bertels moved to Portugal to continue working on the quan- tum computing challenges. As a full professor in Porto, he is in the process of setting up a Eu- ropean quantum computing re- search centre to which already multiple universities or research groups are participating. The current members of the initia- tive are the University of Porto (P), ENSTA, in Brest (F), CEA in Grenoble and Paris (F), the Po- litechnical University in Valencia (E) and the University of Leuven (B). The goal is to work on var- ious accelerator topics and to expand the tools for the different layers. QBee is a company that was created to develop several quantum accelerators and will be active at the international level. To this purpose, QBee will con- tinue working on the tools and algorithms that will be needed once a quantum computational accelerator can be made. computer. So, every word in this units (NPU) like Google’s tensor The content of this article needs article refers to a quantum ac- processing unit (TPU), etc. The further research, but is based on celerator, which in principle will formal denition of an accelerator prof. Bertel’s latest research and operate on the quantum mechan- is indeed a co-processor linked recently published article, and ical principles of superposition to the central processor that is remains his intellectual property. and entanglement. capable of accelerating the exe- cution of specific computational Introduction: Given the recent insights leading intensive kernels, as to speed up There is growing interest in quan- to e.g. Noisy Intermediate-Scale the overall execution according tum computing as the new com- Quantum (NISQ) technology as to Amdahl’s law. We now add two putational direction in which we expressed in [2], we are much classes of quantum accelera- can keep on building ever strong- more inclined to believe that the tor as additional co-processors. er computers. In the remainder first industry-based and soci- The rst one is based on quantum of this article, I will not talk about etally relevant application will be gates and the second is based on a quantum computer but rather a a hybrid combination of a classi- quantum annealing. The classical quantum accelerator [1] as up to cal computer and a quantum ac- host processor keeps the control this point, I have not read a good celerator. It is based on the idea over the total system and dele- article about what that any end-application contains gates the execution of certain a quantum computer is. How- multiple computational kernels parts to the available accelera- ever, what an accelerator is, is and the properties of these parts tors. quite well understood by the are better executed by a par- Computer architectures have semiconductor world as almost ticular accelerator which can evolved quite dramatically over every computational device is be, as shown in Figure 1, either the last couple of decades. The built on transistors used to con- field-programmable gate arrays first computers that were built struct a co-processor that will (FPGA), graphics-processing did not have a clear separa- substantially speedup the overall units (GPU), neural processing tion between compute logic and 26 March 2021
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