News: Research PhD profile related to Chalmers University of TechnologyMon, 30 Jul 2018 11:00:42 +0200 Hansson awarded by Chalmers Foundation<p><b>​​Josef Hansson, PhD student at the Electronics Materials and Systems Laboratory and chair of the MC2 PhD student council, has recently been awarded with a travel grant from &quot;Alice och Lars Erik Landahls stipendiefond&quot;.</b></p><div>The grant, 18 800 SEK, will be used for the 2018 IEEE 68th Electronic Components and Technology Conference in San Diego.</div> <div><br /></div> <div>Text: Susannah Carlsson</div> <div>Photo: Michael Nystås</div>Mon, 02 Jul 2018 13:00:00 +0200 the quest for high-entropy alloys that survive 1500 °C<p><b>​An aero-engine should operate at the highest possible temperature for the best output power and energy efficiency. But today’s metal alloys in the engines need cooling – otherwise they turn into powders. This causes alarming energy losses. Saad Sheikh is on the quest to design optimum alloys that survive ultra-high temperatures.</b></p>​<span style="background-color:initial">High-entropy alloys (HEAs), or multi-principal-element alloys, is a new and growing field, and has gained enormous interest in recent years as potential ultra-high temperature materials. The materials and manufacture researcher Saad Sheikh focuses on developing HEAs with optimum tensile ductility and strength, superior than the current state-of-the-art nickel based superalloys. </span><div><br /><span style="background-color:initial"></span><div>This work is driven by the need to improve the energy efficiency of aerospace and power-generation gas-turbine engines. For example, if cooling of aero-engines can be avoided, the aero-engine output power and energy efficiency would increase up to 50%. Other applications like solar power, fuel cells, materials processing and petro-chemistry can also benefit from the results. </div> <div><br /></div> <div><strong>The aim is to be able to operate engines at higher temperatures </strong>than today. Today’s engines expose the nickel based superalloys inside to temperatures approaching 1200 °C, which is close to 90% of their melting points. In the hottest region of a turbine engine, temperatures are approaching 1500 °C. By using complex cooling systems and coatings the nickel based superalloys can exist in the hottest region but the efficiency gained from operating at higher temperatures is greatly reduced, as the cooling needs extra work.</div> <div><img src="/SiteCollectionImages/Institutioner/IMS/Material%20och%20tillverkning/Saad-Sheikh_250pxl.jpg" alt="Saad Sheikh" class="chalmersPosition-FloatLeft" style="margin:5px" /><br /><span style="background-color:initial;font-family:calibri, sans-serif;font-size:11pt">– </span><span style="background-color:initial">The current situation of higher inefficiency losses is alarming, but also provides opportunity to look for new ground-breaking materials. It is a big but intriguing scientific challenge, says Saad Sheikh.</span><br /></div> <div><br /></div> <div><strong>Saad Sheikh</strong> comes from a materials science background and did his Masters in Materials Processing at KTH in Stockholm. Before joining Chalmers University of Technology as a PhD student, he also worked on mechanical properties of cutting tools within the Swedish industry. He is very interested in alloy development and mechanical properties of new structural and high-temperature materials for sustainable energy systems. He explains the difference between HEAs and conventional alloys. </div> <div><br /></div> <div><span style="font-family:calibri, sans-serif;font-size:11pt;background-color:initial">– </span>Conventional alloys are usually based on one or two principal elements. HEAs consist of at least four principal metallic elements with an atomic percentage of each element between 5 % and 35 %. These multi-component element alloys can enable formation of simple solid solution phases. </div> <div><br /></div> <div><strong>In his research</strong>, Saad Sheikh has strived to improve HEAs in several ways. Firstly he has contributed with improved understanding of the solid solubility in HEAs. Secondly he has proposed a mechanism and route for increasing the ductility in refractory, or heat resistant, HEAs – so-called RHEAs.</div> <img src="/SiteCollectionImages/Institutioner/IMS/Material%20och%20tillverkning/Saad-Sheikh-True-tensile-stress-strain-curve_250pxl.png" class="chalmersPosition-FloatRight" alt="True tensile stress-strain curve for Hf0.5Nb0.5Ta0.5Ti1.5Zr. The inset shows the microstructure at the fractured surface." style="margin:5px" /><span style="font-weight:700"></span> <div><br /></div> <div>Thirdly, which has been the ultimate goal of his work, Saad Sheikh has addressed the balance of mechanical properties and oxidation resistance for RHEAs, aiming at high-temperature applications. </div> <div><br /></div> <div><span style="font-family:calibri, sans-serif;font-size:11pt;background-color:initial">– </span>In studies I have found out that the insufficient oxidation resistance in existing ductile RHEAs is attributed to the failure in forming protective oxide scales accompanied by the accelerated internal oxidation leading to pesting corrosion. Aluminizing is a promising solution.</div> <div><br /></div> <div><em>Image: </em><span style="background-color:initial"><i>True tensile stress-strain curve for the as-cast Hf0.5Nb0.5Ta0.5Ti1.5Zr. The inset shows the microstructure at the fractured surface.​</i></span></div> <div><span style="background-color:initial"><i><br /></i></span></div> <div>These studies provide important input to the further development of RHEAs as novel high-temperature materials and shed light on the design of refractory HEAs with optimal mechanical as well as heat and oxidation resistance properties.</div> <div><br /></div> <h2 class="chalmersElement-H2">FACTS</h2> <div>Saad Sheikh belongs to the division of <a href="/en/departments/ims/research/mm/Pages/default.aspx">Materials and Manufacture</a> at the department of <a href="/en/departments/ims/Pages/default.aspx">Industrial and Materials Science</a>. He recently presented his doctoral thesis with the title: </div> <div><a href="" target="_blank">Alloy Design for High-Entropy Alloys: Predicting Solid Solubility, and Balancing Mechanical Properties and Oxidation Resistance</a></div> <div><br /></div> <div>If you want to learn more about refractory high-entropy alloys, we recommend to read:</div> <div><a href="" target="_blank">Alloy design for intrinsically ductile refractory high-entropy alloys, published 2016 in the prestigious Journal of Applied Physics.</a></div> <div><br /></div> <div>Saad Sheikh has been granted a postdoc fellowship by the Swedish Foundation for Strategic Research (SSF) and the Japan Society for the Promotion of Science (JSPS). He will be placed in Japan at the <a href="" target="_blank">National Institute for Materials Science in Tsukuba</a>, with focus on ultra-high temperature materials (alloy design and mechanical properties) for two years. </div> <div><br /></div> <div>Please contact <a href="/en/staff/Pages/sheng-guo.aspx" title="Link to profile page of Sheng Guo" target="_blank">Associate Professor Sheng Guo​</a>, Saad Sheikh's supervisor for more information</div> <div><br /></div> <div><strong>RELATED NEWS</strong></div> <div><a href="/en/departments/physics/news/Pages/Ground-breaking-discoveries-could-create-tougher-alloys-with-many-applications.aspx" target="_blank">Superior alloys could be possible, thanks to ground-breaking research</a></div> <div><br /></div></div> ​<div><em>Text: Nina Silow</em><br /><em>Images: Airbus, Nina Silow and Saad Sheikh</em></div> ​Wed, 27 Jun 2018 00:00:00 +0200 new bridge between statistics and computational mathematics<p><b>In her doctoral thesis, Kristin Kirchner has formulated an approach for solving a specific class of stochastic partial differential equations (PDEs) approximately and efficiently. One of its applications is spatial prediction in statistics, such as weather prognosis.</b></p><p>​<img class="chalmersPosition-FloatRight" alt="Photo Kristin Kirchner" src="/SiteCollectionImages/Institutioner/MV/Nyheter/KristinKirchner250x300.jpg" style="margin:5px" />The thesis consists of two parts, where the first one is rather theoretical. The second part is a collaboration between numerical mathematics, which is Kristin’s field of expertise, and spatial statistics and it has direct applications. In the first part, a stochastic PDE in both space and time is considered and its covariance structure between different time points, which is a deterministic quantity, is characterized by a deterministic PDE. Subsequently, numerical methods for solving this are proposed and investigated.</p> <p>The motivation for the second part of the thesis are applications in spatial statistics. There are numerous phenomena that we want to predict – such as weather, ozone content, or pollen count. Their forecasts are typically based on statistical models for which one assumes that at every considered location the quantity of interest (as temperature, pollen, or ozone) is random, i.e., it is modelled by a random field. Even though a specific outcome of such a field is random, its behaviour follows certain mathematical laws. Gaussian random fields form a specific class of these fields and the mathematical law characterising them is, in a sense, simple and practical, since it is uniquely determined by the mean and the covariance structure of the field. </p> <h4>Simulating Gaussian Matérn fields with general smoothness</h4> <p>Kristin has worked on Gaussian Matérn fields (Bertil Matérn was a Swedish forestry statistician) which are Gaussian random fields with a specific covariance structure determined by three parameters: the variance, the correlation range, and the smoothness of the field. More precisely, she has considered the problem of computing solutions to a specific class of fractional order stochastic PDEs which have the property that their solutions are approximations of Gaussian Matérn fields. In addition, there is a one-to-one correspondence between the value of the fractional order of the stochastic PDE and the smoothness parameter of the Matérn field. </p> <p>By formulating a method for solving these stochastic PDEs approximately and quickly with a computer, an efficient way to simulate realisations, i.e., possible outcomes of Gaussian Matérn fields, is obtained. While earlier approaches restricted the value of the fractional order, this numerical approximation allows for a general fractional order and, thus, for a general smoothness of the Matérn field. As mentioned above, simulating these fields is of importance for predictions in spatial statistics, for which the method has been used within the scope of a collaboration between numerical mathematics and spatial statistics. </p> <h4>From Ulm to ETH to Chalmers, and then?</h4> <p>During her master’s studies Kristin spent one year as a visiting student at ETH Zürich. Among other courses she took one on numerical analysis for stochastic PDEs, taught by Andrea Barth and by Annika Lang, who later became a member of the Department of Mathematical Sciences at Chalmers. Even though the subject for her master’s thesis back home at Ulm University in Germany was on numerical methods for deterministic PDEs, Kristin strongly felt that she wanted to do research on stochastic problems within the scope of a PhD – mostly since it involves different fields of mathematics, namely numerical mathematics, functional analysis, and probability theory. Annika Lang recommended her Stig Larsson as a possible supervisor for this. Kristin applied for an open PhD position in mathematics, and on the same day that she was interviewed in Gothenburg she was also offered a position, which she decided to accept.</p> <p>In retrospect, Kristin is very pleased about her decision. She felt welcome from the first day at the Department of Mathematical Sciences and she will for sure stay in contact with her three supervisors Stig, Annika, and Mihály Kovács. As her final teaching duty, she gave a PhD course on computational finance – a challenge since, except being official examiner, she was responsible for everything, but also a very good experience. Outside the academic life Kristin believes that she will miss the landscape with all the islands, Liseberg for which she bought a Gold Pass for this last year, the good Bergstrands coffee in Café Bulten, and the high quality and great range of food – in particular, of cheese and seafood. As for now Kristin has decided to stay in academia for a postdoc, but it is still an open question where she will go next.<br /><br /><em>Kristin Kirchner will defend her PhD thesis “Numerical Approximation of Solutions to Stochastic Partial Differential Equations and Their Moments” on May 29 at 10.15 in the room Pascal, Hörsalsvägen 1. Supervisor is Stig Larsson, co-supervisors are Annika Lang and Mih&#19;ály Kov&#19;ács.</em><br /><br /><strong>Text and photo</strong>: Setta Aspström</p>Wed, 23 May 2018 16:20:00 +0200 to make kitchen pots harder<p><b>​New research shows that tailor-making the material used when making stainless steel is the key to optimize hardness and corrosion free properties. This new knowledge is important for oil, gas, food and nuclear industries – and for your kitchen pots.</b></p>​<img src="/SiteCollectionImages/Institutioner/IMS/Material%20och%20tillverkning/Giulio%20Maistro_200x250.png" class="chalmersPosition-FloatRight" alt="Giulio Maistro" style="margin:5px;width:170px;height:213px" /><span style="background-color:initial">In a recently published doctoral thesis, <a href="/sv/personal/Sidor/maistro.aspx" target="_blank">Giulio Maistro</a> presents studies of methodologies to make austenitic stainless steel harder, without losing the &quot;stainless&quot; properties. The results show that it is important to consciously balance the different metals used in the steel, as well as the additives nitrogen and carbon.</span><div><br /></div> <div><strong>Austenitic stainless steel </strong>is a specific type of stainless steel alloy that is used for kitchen pots and many industrial applications. This type of material is very good to use with strong acids or salty water because it is resistant to corrosion. </div> <div><br /></div> <div><span style="background-color:initial">Unfortunately, today’s stainless steel has the drawback of being very easy to scratch and damage. It is too soft. This is not crucial for our kitchen ware, but is a big problem for jewellery or for industrial applications. In industrial sectors like the oil, gas, food and nuclear industries, the surface has to be smooth like a mirror. </span><br /></div> <div><br /></div> <div><strong>When making stainless steel</strong>, it is the combination of the material in itself and the surface treatment that defines how good the result is. The result of a surface treatment can be radically different depending on the formula the material is composed of. Giulio Maistro says that this can be both a good and a bad thing. </div> <div><span style="color:black;font-family:calibri,sans-serif;font-size:11pt;background-color:initial"><br /></span></div> <div><span style="color:black;font-family:calibri,sans-serif;font-size:11pt;background-color:initial">– </span>Nowadays, we have reached a stagnation in the application of surface treatments like plasma, gas nitriding or carburizing. More or less everyone in the field knows &quot;when it is worth to use them and when it is not&quot;. </div> <div><br /></div> <div>According to Giulio Maistro, companies keep their processes secret which makes process development hard and almost completely abandoned in academia. Giulio Maistro’s research is welcomed. Not much research has been done earlier on the optimization of the materials to fit the treatment. Instead of trying to change and over-optimize the treatment parameters, it could be easier and more effective to tailor-make a new material that better matches the treatment.</div> <div><br /></div> <div><strong>This tailor-making involves</strong> <strong>Nickel and Molybdenum</strong>, two metals that typically are added into the steel to improve resistance against corrosion. </div> <div><span style="color:black;font-family:calibri,sans-serif;font-size:11pt;background-color:initial"><br /></span></div> <div><span style="color:black;font-family:calibri,sans-serif;font-size:11pt;background-color:initial">– </span>In my research I show that by adding Nickel it is possible to decrease the unwanted formation of carbides, which are bad for corrosion. However, when too much Nickel is used, the material cannot be hardened very much. This is because carbon and nitrogen do not like Nickel and vice versa. If you use the metal Molybdenum, the opposite effect is shown. </div> <div><br /></div> <div>To harden the steel, it is common to introduce nitrogen or carbon in it. The more nitrogen or carbon you have, the harder the steel gets. This relates to Nickel and Molybdenum. Depending on how much of those metals you have in the steel, you can change how much nitrogen or carbon you can introduce in it. </div> <div><br /></div> <div>However, if you introduce too much nitrogen or carbon, chemical compounds called nitrides and carbides are formed. When they form, the stainless property of the steel gets lost. In general, Molybdenum increases the amount of nitrogen or carbon you can insert. Nickel limits the amount but also limits the formation of nitrides or carbides. </div> <div><span style="color:black;font-family:calibri,sans-serif;font-size:11pt;background-color:initial"><br /></span></div> <div><span style="color:black;font-family:calibri,sans-serif;font-size:11pt;background-color:initial">– </span>This new knowledge shows that companies that manufacture products made of stainless steel need to find a balance between Nickel and Molybdenum to get the maximum hardness while maintaining the stainless properties, upon introducing nitrogen or carbon, says Giulio Maistro.</div> <div><br /></div> <div><strong>FACTS:</strong></div> <div>Gas nitriding or carburizing are methods to introduce nitrogen or carbon to the steel.</div> <div><br /></div> <div><a href="/sv/personal/Sidor/maistro.aspx" target="_blank">Giulio Maistro​</a> performed his doctoral studies at the <a href="/en/departments/ims/research/mm/Pages/default.aspx">division of Materials and Manufacture</a> which belongs to the <span style="background-color:initial"><a href="/en/departments/ims/Pages/default.aspx">department of Industrial and Materials Science</a> at <a href="/en/Pages/default.aspx">Chalmers University of Technology</a>. He </span><span style="background-color:initial">successfully defended his doctoral thesis on January 26th. The title of the thesis is: </span></div> <span></span><div><em>Low-temperature carburizing/nitriding of austenitic stainless steels - Influence of alloy composition on microstructure and properties.</em></div> <div><br /></div> <div><strong>Read more in this scientific article:</strong></div> <div><a href=""></a></div> <div><br /></div> <div><em>Text: Nina Silow</em></div> <div><em>Photo in the article: Marcus Folino</em></div> ​Tue, 20 Mar 2018 00:00:00 +0100 selection of truck tyres saves fuel<p><b>​The PhD thesis of Zuzana Nedělková concerns the optimal selection of tyres for a variety of vehicle configurations as well as operating environments, analyzed from a mathematical optimization point of view.</b></p><p><img width="300" height="323" class="chalmersPosition-FloatLeft" alt="Illustration truck and tyres" src="/SiteCollectionImages/Institutioner/MV/Nyheter/CoverFigure300x.png" style="margin:5px" />The goal of the project has been to improve the tyre selection at Volvo Group Trucks Technology, through developing a methodology using mathematical optimization. Volvo wants to give recommendations to their truck users of which tyres they should select, in order to save fuel. This is done when the tractive energy required to run the vehicle is reduced. Which tyres are optimal depends on many aspects, such as the environment where the truck will be used, how the load will be distributed, and the model of the truck. This create lots of optimization problems, that needs to be solved almost instantly as the customers should not have to wait for an answer.</p> <p>Zuzana has developed a splitting algorithm for a large number of instances of simulation-based optimization problem with categorical variables of no natural order. A database of strategic vehicle specifications and their usage of the vehicles has been set. In that way a lot of the computation is done beforehand, and when a new customer arrives it is possible to identify the optimal tyres using the solutions in the database.</p> <p>When the algorithm was tested, the results showed that up to 3% of the tractive energy can be saved with the optimal tyres selected when compared to the tyres that are sold with the truck. The methodology can however not be applied immediately. There is a new project on its way to propagate tyre data, the vehicle models need to be developed automatically, and more data is also needed from the tyre suppliers. When these parts are solved, the project is ready to be implemented. </p> <p><img width="250" height="300" class="chalmersPosition-FloatRight" alt="Photo Zuzana Nedelkova" src="/SiteCollectionImages/Institutioner/MV/Nyheter/ZuzanaNedelkova250x300.jpg" style="margin:5px" />The project was initiated by Volvo Group Trucks Technology and is also funded by the Swedish Energy Agency. The optimization group at the Department of Mathematical Sciences has cooperated with the Department of Mechanical and Maritime Sciences, to develop the vehicle model, the Institute of Technology at the University of Ontario, to develop the tyre model, and Fraunhofer-Chalmers Research Centre Industrial Mathematics, to develop the algorithm models.</p> <p>Zuzana took a master course in optimization at Chalmers in 2010 through the Erasmus programme, and found that she liked the subject a lot. The PhD project she has now completed was announced at the time she finished her master studies, she took a chance, and so it happened that she stayed in Sweden six more years than originally intended. After her dissertation she will however move back to the Czech Republic, where she will work with optimization of electric grids for an electric power distribution company.</p> <p>– This has, overall, been a good experience. A very positive part of it is the Swedish parental leave system, allowing to combine career and family very easily.<br /><br /><em>Zuzana Nedělková will defend her PhD thesis “Optimization of truck tyres selection” on February 22 at 10.15 in the room Pascal, Hörsalsvägen 1. Supervisors are Ann-Brith Strömberg and Peter Lindroth, co-supervisors are Michael Patriksson and Bengt Jacobson.</em><br /><br /><strong>Text and photo</strong>: Setta Aspström<br /><strong>Illustration</strong>: Zuzana Nedělková (cover of the PhD thesis)</p>Tue, 13 Feb 2018 09:10:00 +0100 for his work on engine pollution control<p><b>​​Reducing pollution from engine exhaust is an important and very challenging task in our society. Physics Doctor Maxime Van den Bossche has worked out models that explain how molecules “dance” on the surfaces during catalytic reactions. This knowledge can be used to understand how the exhaust from natural gas engines can be cleaned efficiently.</b></p><div>Recently, Maxime Van den Bossche’s work was awarded The Best Thesis Award 2017 by the Department of Physics at Chalmers University of Technology – the department where he defended his doctoral thesis last spring. <p></p> <div>&quot;His work is an impressive mix of theory development, computations and experimental collaborations all combined to help solving an important environmental issue,&quot; says Henrik Grönbeck, Professor of Physics at Chalmers and main supervisor of Maxime Van den Bossche. <p></p> <img src="/SiteCollectionImages/Institutioner/F/Blandade%20dimensioner%20inne%20i%20artikel/avhandling_figur_2.300x.jpg" class="chalmersPosition-FloatRight" width="266" height="266" alt="" style="margin:5px" />During his time at Chalmers, Maxime contributed to a knowledge-platform that can be valuable anywhere where catalysts are used.  For example, several insights can be of interest for the chemical, transportation and oil industries. His model has already been used for analysing engine exhaust from ships and his work is of importance for leading engine manufacturers and operators. <p></p> <div>He  has also contributed with a substantial amount of peer-reviewed publications, many of which were a collaboration between experimental and theoretical teams.<p></p> <div>“I’m happy that my thesis can be useful – both for society and for researchers in my field. It was very rewarding to write the thesis and of course it’s nice to get this additional appreciation and an award for the hard work too, “expresses Maxime, who has been working at the University of Iceland in Reykjavik after he finished his studies at Chalmers.  <p></p> <div>He has recently started a post-doc position at the Department of Chemistry at Brown University in Rhode Island, USA. He will be working to provide a better understanding of the electro-reduction of carbon dioxide. <p></p> <div>“It’s a challenging type of research, with many new topics for me to learn, and I’m really looking forward to it!”<p></p> <div>Maxime Van den Bossche defended his doctoral thesis at Chalmers University of Technology in March 2017. The work was conducted at the Competence Centre for Catalysis and the Division of Chemical Physics at the Department of Physics. The title of the thesis is <a href="/en/departments/physics/calendar/Pages/Doctoral-thesis-Maxime-van-den-Bossche.aspx">&quot;Methane oxidation over palladium oxide - From electronic structure to catalytic conversion&quot;. Read the abstract here.</a><p></p> <div>Text: Mia Halleröd Palmgren, <a href=""></a><p></p> <h3 class="chalmersElement-H3">The Best Thesis Award at the Department of Physics  </h3> <p></p> <div>The prize was founded in 2013 and is awarded annually to one or several doctoral students who have defended their thesis during that year. Besides the honor, the winner also gets a diploma and a monetary prize of SEK 10.000. The prize committee consists of researchers from every division within the department. <p></p> <div>The members of this year’s committee were Riccardo Catena, Paolo Vinai, Paul Erhart, Arkady Gonoskov, Marianne Liebi, Björn Agnarsson, Jonathan Weidow, Philippe Tassin, Igor Zoric and Timur Shegai. <p></p> <h4 class="chalmersElement-H4">The prize committee about the awarded thesis 2017:</h4> <p></p> <div> &quot; Maxime Van den Bossche has written an exceptionally good thesis. The structure of the thesis, well-written story, coherent flow of information, combined with a pedagogical description of the topic, make it a good read for anyone who would like to learn more about DFT. During his PhD project, Maxime has also contributed with a substantial amount of peer-reviewed publications, many of which were a collaboration between experimental and theoretical teams. Altogether, this made us choosing Maxime's work for the best PhD thesis award this time. The prize committee sincerely congratulates both Maxime and his supervisor Henrik Grönbeck with this achievement and wishes them success in the future.&quot;</div> <p></p> <div><a href=""><img class="ms-asset-icon ms-rtePosition-4" src="/_layouts/images/icgen.gif" alt="" />See the list of previous winners and detailed criteria for the award.</a></div></div></div></div></div></div></div></div></div></div></div> Tue, 30 Jan 2018 00:00:00 +0100 wants to stop dangerous vibrations<p><b>Industrial PhD student Hans Lindell from Swerea IVF has worked to reduce and investigate how vibrations affect humans for almost 30 years. Recently, he was elected chairman of an international standardization committee working with vibrations. In the committee, he wants to try to influence the standard so that dangerous vibrations can be stopped.</b></p>​<span style="background-color:initial">Vibration damage is the most common occupational disease in Sweden. Every day, 400,000 people work for more than two hours a day with vibrating machines. This causes a large number of chronic damage to the nerves, vessels, muscles and skeletal system. But it doesn’t have to be like this.</span><div><br /></div> <div> - Machines don't need to vibrate and hurt people! There is no physical law that confirms that” says Hans Lindell, who has shown that machines with significantly lower vibrations can be developed.</div> <div><br /></div> <div>With help from research results, it has been possible to rebuild existing machines, such as chisel hammers and nutrunners, to show that it is possible to greatly reduce vibration levels. Two types of vibrations that are attempted to counteract are rotating and translating that goes back and forth. One of the techniques used is called ATVA (Auto Tuning Vibration Absorber) and is based on vibration reductions by counteracting the forces that cause the vibrations. Prototypes are currently being tested in the field with satisfactory results. Recently, the project was also awarded additional funds from Vinnova to scale up the project and introduce prototypes in vibration-free, industrial demonstration environments in full production.</div> <div><br /></div> <div>Hans Lindell thinks that his extensive experience in the field was the reason for him being elected as chairman of the International Standardization Committee named ISO/TC108/SC4/WG3. One of the standards under the group's responsibility is ISO 5349, which states how to measure and assess the risks of vibrations on handheld tools. Hans Lindell thinks that it feels both nervous and at the same time very fun to get the presidency.</div> <div><br /></div> <div>- There is a great need for an adjustment of the current standard so that it also takes into account machines with impacts and shocks that give high frequency vibration which we suspect cause a large part of the damage. As a chairman, you will be able to drive a change&quot; says Hans Lindell.</div> <div><br /></div> <div>A lot of things are already about to happen thanks to Hans Lindell's research. Machines, where the high-frequency vibration is remedied, will be released on the market within one year. As far as ATVA technology is concerned, it probably takes a few years, but future users will get fewer injuries, machine manufacturers get an opportunity to increase their competitiveness and society earns on reduced costs for a disease. However, there is much more to be found in the vibration area. The ATVA technology is applicable to considerably more uses than handheld machines. There is a lot of applications where vibrations need to be reduced.</div> <div><br /></div> <div> - What's so funny is that the deeper you get into a problem, the more unanswered questions are found&quot; says Hans Lindell</div> <div><br /></div> Thu, 23 Nov 2017 14:00:00 +0100 outlook on wasted food at sea<p><b>​Wasted food is a global problem, around 1/3 of food produced for humans is wasted or lost. But while the topic is widely discussed on land, food waste generated on ships seems not to receive similar attention. In her thesis, “Management of ship-generated food waste – illustrated from the Baltic Sea perspective”, PhD Magda Wilewska-Bien, at Chalmers, analyses current management of ship-generated food waste in the Baltic Sea region and discuss effective solutions.</b></p>​<img src="/SiteCollectionImages/Institutioner/SMT/Profilbilder/Wilewska-Bien-M.jpg" class="chalmersPosition-FloatLeft" alt="" style="margin:5px" /><span style="background-color:initial">The Baltic Sea is the largest brackish sea in the world and is classified by the International Maritime Organization, IMO as a Particularly Sensitive Sea Area. Being an almost enclosed basin, the Baltic sea suffers from eutrophication due to inflow of nutrients, phosphorus and nitrogen and a low water exchange frequency. Under eutrophication conditions, marine ecosystems are characterized by intense algal growth, increased oxygen consumption, oxygen depletion with recurrent internal loading of nutrients and death of benthic organisms.</span><div>Phosphorus and nitrogen in the waste discharged from ships are low compared to the total load of nutrients that enter the Baltic sea. However, the shipping in the Baltic Sea is intense and expected to increase, one of the key goals by the European Commission is a shift of medium distance passenger and freight journeys from road to rail and waterborne transport. And with increasing growth of maritime transport and cruise shipping, effective food waste management becomes a pressing issue, Magda Wilewska-Bien writes in her thesis.</div> <div><br /></div> <div><strong>Food waste excepted from regulations</strong></div> <div>In the Baltic Sea discharges of sewage from passenger ships will soon be prohibited, but food waste and grey water (wastewater from dishwashing, shower, laundry etc.) are not included in the coming regulations. Food waste can either be stored for disposal in the port or handled at sea. It is allowed to, with some exceptions and limitations, to discharge ground food waste at sea when the ship is moving at the distance of minimum 12 nautical miles from nearest land and the food waste pieces should not be larger than 25mm.</div> <div><br /></div> <div>It’s a challenge, Marie Wilewska-Bien writes, to get a clear picture on how much food waste that is disposed in the Baltic Sea ports since much information is not publicly available. But an estimation is that the food waste from cargo ships is 0,2-0,5 kg per person and day. For cruise ships 2kg per person and day. An earlier study made in Norwegian waters showed that about 2% of the total generated food waste was discharged to the sea from passenger ships, 40% from bulk carrier, 52% from dry bulk carrier and 92% from general cargo vessel.</div> <div><br /></div> <div><strong>Recover phosphorus</strong></div> <div>The annual contributions of nutrients from ship generated food waste is about 182 tonnes nitrogen and 34 tonnes phosphorus. In the light of an expected global phosphorus scarcity, there is a potential to recover phosphorus and therefore it is preferable to encourage ships to dispose the waste ashore where it can be recycled further to recycle the phosphorus.</div> <div><br /></div> <div>In Magda Wilewska-Biens thesis, a sustainable solution for ship-generated food waste is based on three pillars: the food waste should be separated from other waste streams (1) it should be measured (2) and constantly reduced (3). It should preferably be disposed onshore, where it further is managed to recover energy and valuable constituents.</div> <div><br /></div> <a href=""><div>Read Magda's thesis here &gt;&gt;</div> <br /></a><div><em>Text by <a href="" target="_blank">Lighthouse</a></em></div> Mon, 02 Oct 2017 00:00:00 +0200 have a free PhD position<p><b>​“Free” PhD positions, that is, the specialisation within the research field is not determined from the beginning, is somewhat unusual at the university at large but usual in mathematics. Linnea Hietala and João Pedro Paulos are two of the PhD students who are employed at free positions.</b></p><p>​<img class="chalmersPosition-FloatRight" alt="Photo Linnea Hietala" src="/SiteCollectionImages/Institutioner/MV/Nyheter/linneahietala200x250.jpg" style="margin:5px" />Linnea read freestanding courses at the Mid Sweden University, initially at a distance, which she put together for a master’s degree. She has always wanted to study something with mathematics and thought it felt natural to continue to PhD studies. When it was time to apply she found free positions in Göteborg and Uppsala, and Göteborg was first in offering a position.</p> <p>– I did not really know what I wanted to specialise in, only that it would be fun with something else than complex analysis which the Mid Sweden University focused on. The director of postgraduate studies suggested three different supervisors whom I spoke to, and then I had Hjalmar Rosengren as a first-year supervisor. It felt good, so I have continued on that track, which deals with lattice models in the area of physical combinatorics, which in the long run can be used by physicists. Jules Lamers, who began as a postdoc and became my co-supervisor, has also meant a lot for me to get into the area.</p> <p><img class="chalmersPosition-FloatLeft" alt="Photo João Pedro Paulos" src="/SiteCollectionImages/Institutioner/MV/Nyheter/joaopedropaulos200x250.jpg" style="margin:5px" />João began his university studies in physics at Instituto Superior Técnico, in Lisboa. However, he soon found out that it was mathematics he really enjoyed. The subject of his master thesis was operator algebras, and then the plan was to continue with a PhD in Lisboa. But due to unexpected policy changes there were no grants that year and João had to reconsider. He had a period of doubt if he would be good enough for a PhD position and sent his CV to different companies, but realised that he at least should try. He then looked for free positions in Sweden and Denmark. </p> <p>– I did not know much about the universities there except their existence, but the Nordic countries have a reputation of being tolerant, relaxed and comfortable, as well as peaceful and serene. Besides, there is also the weather – I really like the cold! As said, I looked for free positions, as I did not find any concrete project with which I would feel comfortable. I have had Maria Roginskaya as my first-year supervisor and I am now working on a special problem in functional analysis. This first year has been a bit experimental and there is still some flexibility as to what my dissertation will be about. In the long run, I would like to work on a topic involving set theory and functional analysis.</p> <p>Both Linnea and João think that the teaching part of the positions is a big advantage. Linnea, who now begins her third year, is now responsible for the mathematical part in a course for future primary school teachers at the Faculty of Education. She has taught future teachers for all age categories, but also future civil engineers. To be a teacher was a childhood dream she had, and she also taught half a year at upper-secondary schools in Sundsvall before beginning her PhD position. She still finds teaching fun, and she likes when the course coordinators have clear thoughts about what they want with the course and are able to convey them to exercise supervisors and others. </p> <p>For João, the teaching duties that came with the position were one of the most appealing things about it and something he at least could feel really comfortable with. Last year he held exercises in linear algebra, through an agreement that he could do it in English. In retrospect, he regrets that he neglected to learn Swedish during his first year since this narrows down the selection of courses he could teach. This semester he just has Matlab classes. He tries to give them in a way which is interesting and appealing to the students. Nevertheless, he hopes he will teach other non Matlab classes in the future, as he considers that he can be more useful for the students on those.</p> <p>Linnea nevertheless finds it was a bit difficult with the free positions since she did not know the research areas here and who were working in them. She believes that it probably feels different if you have done the undergraduate education here as well. It is also somewhat confusing with the different rules for Chalmers and the University of Gothenburg, as well as the fact that the divisions and graduate schools have different boundaries, which makes it difficult for the PhD students to ask each other about what is applicable. But the Committee for PhD studies at the department, which Linnea is a member of, now works for a joint degree that applies to both universities, which will facilitate. She is also one of the organisers of the welcome meeting for new PhD students and a new buddy programme for them.</p> <p>João still has a mostly positive view of PhD life in Sweden. His biggest impression is of how relaxed and helpful people are. He likes that the academic life is not very hierarchical, as for example that you do not have to use titles all the time, and that the university cares about the personal time of the employees. Chalmers helped him in finding somewhere to live, which otherwise might be one of the greatest obstacles in Göteborg, and he experienced no big administrative problems when moving here. João, as well as Linnea, shares office with another PhD student, but neither of them have had any problems with this. And the conditions in terms of equipment he thinks are really good.<br /><br /><strong>Text and photos</strong>: Setta Aspström</p>Fri, 29 Sep 2017 13:35:00 +0200 understand bacterial communities<p><b>​The PhD thesis of Mariana Buongermino Pereira develops statistical models that provide an increased understanding of metagenomics data, that is, genetic material recovered directly from environmental samples. Mariana has studied horizontal gene transfer and methods to get rid of systematic noise.</b></p><p>​<img class="chalmersPosition-FloatRight" alt="Photo Mariana Buongermino Pereira" src="/SiteCollectionImages/Institutioner/MV/Nyheter/marianapereira250x300.jpg" style="margin:5px" />When dealing with biological phenomena which are random, not deterministic, the best way to describe them are through probabilistic models. Thus, we get a better understanding of the phenomena, so that we can make predictions on new data. Mariana studies DNA sequencing data. The human genome project, when all genes of the human genome were identified and mapped, was complete in 2003. Since then, lots of improvements have been made in the DNA sequencing techniques, which are known as NGS, next generation sequencing. These technologies generate lots of data and careful work is needed to make sense of them, not least to determine what is signal and what is noise. Because of the high variability involved in the techniques, and intrinsic to the biological process of interest, statistics is the best way to do this. </p> <h4 class="chalmersElement-H4">Bacteria exchange genes between cells to adapt to the environment</h4> <p>Mariana’s research involves bacterial communities from the environment, from which samples have been taken and all DNA of the microorganisms in them have been sequenced. In these communities, she has studied horizontal gene transfer, the ability that bacteria have to exchange genes between cells. She focuses in one genetic mechanism that allows horizontal gene transfers, called integrons. The genes that have been transferred via integrons have a marker and a model of this marker is made to see what the bacteria are transferring and how they evolve to better adapt to their environment. In particular, this is a mechanism bacteria can use to become resistant against antibiotics. The 13 000 genes that have been found are from all sorts of environments – from oceanic samples, from the Amazonas, from geysers and from the guts of humans and elephants. They carry all sorts of different functions, although the majority do not correspond to any known function, indicating that further studies on this topic are required.</p> <p>Also, metagenomics data can explain how communities differ in the genetic level. For example, we can investigate if more antibiotic resistance genes are found in a polluted environment than in a pristine environment, or what bacterial genes are found in the gut of a patient with a disease compared to the gut of a healthy person. Usually in these comparisons between communities there is very much noise among the data. The second part of the thesis deals with the removal of this noise. Mariana have compared nine normalization methods to get rid of systematic noise, and the results show that some methods can produce high levels of false positives, and highlight the importance of using a suitable method. The thesis can be used as a guidance on how to analyse metagenomic data to better understand microbial communities. Also, the data of the 13 000 genes that have been found can easily be downloaded and used in other studies.</p> <h4 class="chalmersElement-H4">Master programme in Bioinformatics led to PhD position </h4> <p>When Mariana began her studies at the University of São Paulo she took the new programme Medical physics. She liked physics, mathematics and biology, which she was very curious about, but she did not want to read only one of the subjects. Medical physics, however, did not turn out to be exactly her thing. She finished her bachelor degree, moved to Sweden, and found the master programme Bioinformatics. In one of the courses there she met her current supervisor Erik Kristiansson, who recommended her to apply for the doctoral position she has held.</p> <p>– I would say about everything in Sweden is different from Brazil. What I really like in the academic life is the low hierarchical levels, that the professors and supervisors talk to you as to an equal and listen to your ideas.</p> <p>Next stop for Mariana is London, where she will have a three-year postdoctoral position at the Institute of Cancer Research. She has worked a little bit with cancer as well, although the paper has not been published yet. Still, the techniques she will use for her postdoc are the same as in her doctoral work. More specifically, she will work with identification of the driver mutations in prostate cancer. Mariana finds the cancer problems interesting and challenging, and she wants to see results of the research in a relatively near future. She also looks forward to move to London, even if she would be glad to return to Sweden in the future.<br /><br /><em>Mariana Buongermino Pereira will defend her PhD thesis “Statistical modelling and analyses of DNA sequence data with applications to metagenomics” on September 22 at 10.15 in the room Pascal, Hörsalsvägen 1. Supervisor is Erik Kristiansson, co-supervisor is Marija Cvijovic</em>.<br /><br /><strong>Text and photo</strong>: Setta Aspström</p>Thu, 14 Sep 2017 14:50:00 +0200 research is highlighted in Electronics Letters<p><b>​​Ewa Simpanen, PhD student at the Photonics Laboratory at MC2, gets attention for her research in the June issue of the renowned scientific journal Electronics Letters.</b></p>Electronics Letters is internationally renowned for its rapid communication of new developments and emerging topics across the broad and interdisciplinary field of modern electronics and electrical engineering.<br /><br />In the June 2017 issue, the turn came to Ewa Simpanen, who's research interests concern lasers for data communication. She is being interviewed in the new issue, in which her latest scientific paper – co-written with colleagues at Chalmers and Hewlett Packard Enterprise in the U.S – is published as well.<br /><br /><img src="/SiteCollectionImages/Institutioner/MC2/News/vcsel_array_350px.jpg" class="chalmersPosition-FloatRight" alt="" style="margin:5px" />Ewa Simpanen's research is about increasing the wavelength for low-cost laser and fiber technology to meet the growing needs of optical interconnects in the massive data centres – operated by giant service providers like Facebook and Google – that underpin our Internet-enabled world. <br />“The purpose of this work is to develop high-speed, longer wavelength those while still using the GaAs-based material systems as it enables the fabrication of VCSELs which are superior to those based on other material systems in terms of speed, efficiency, manufacturability, and cost”, says Ewa Simpanen.<br /><br />In the June issue of Electronics Letters she and her colleagues present a VCSEL design operating at 1060 nanometer, equal to one millionth of a metre.<br />“We have limited the wavelength extension to 1060 nm since the long-term reliability of GaAs-based VCSELs may be compromised if extending the wavelength beyond ∼1100 nm”. It is a longer wavelength than the current GaAs standards, located at 850 and 980 nm, to reduce chromatic dispersion and attenuation in the fiber, which is crucial for reaching the longer ranges of data centers. We have tried to find a sweet spot with the wavelength in between, explains Ewa Simpanen for Electronics Letters.<br /><br />VCSEL means vertical-cavity surface-emitting laser.<br /><br />Text and photo: Michael Nystås<br /><br />Caption: <br />A microscope image of an array of VCSEL devices on chip; newly fabricated and ready for characterisation.<br /><br /><a href="">Read the article in Electronics Letters</a> &gt;&gt;&gt;<br /><br />Source: Electronics Letters, Volume 53, Issue 13, 22 June 2017, page 819<br />DOI:  10.1049/el.2017.2117 , Print ISSN 0013-5194, Online ISSN 1350-911X<br />Tue, 08 Aug 2017 09:00:00 +0200 a source for future antibiotics<p><b>​Fungi is a potential goldmine for the production of pharmaceuticals. This is shown by Chalmers researchers, who have developed a method for finding new antibiotics from nature’s own resources. The findings could prove very useful in the battle against antibiotic resistance.</b></p>​Antibiotics have saved millions of lives since they were discovered in the 1940s. But recently we’ve had to learn a new term; antibiotic resistance. More and more bacteria are developing their own protection against antibiotics, thereby becoming resistant to treatment. This will lead to simple infections getting lethal once again, and our need for new antibiotics is urgent.<br /><br />The first antibiotic being mass-produced was penicillin, derived from the Penicillium fungi. Looking for new antibiotics, Chalmers researchers sequenced the genomes of nine different types of Penicillium species. And the findings are amazing:<br /><br />– We found that the fungi has an enormous, previously untapped, potential for production of new antibiotics and other bio-active compounds, such as cancer medicines, says Jens Christian Nielsen, a PhD student at the Department of Biology and Biological Engineering.<br /><br />In the study, recently published in the journal Nature Microbiology, the research group scanned the genomes of 24 different kinds of fungi to find genes responsible for the production of different bio-active compounds, like antibiotics. More than 1000 pathways were discovered, showing an immense potential for fungi to produce a large variety of natural and bio-active chemicals that could be used as pharmaceuticals.<br /><br />In about 90 cases, the researchers were able to predict the chemical products of the pathways. As an evidence of this, they followed production of the antibiotic yanuthone, and identified a new version of the drug produced by species not previously known to produce it.<br /><br />All in all, the study show a vast potential for fungi, not only in producing new antibiotics but also in enabling a more efficient production of old ones – and maybe also more effective versions of the older ones.<br /><br />– It’s important to find new antibiotics in order to give physicians a broad palette of antibiotics, old as well as new, to use in treatment. This will make it harder for bacteria to develop resistance, Jens Christian Nielsen explains.<br />– Previous efforts on finding new antibiotics have mainly focused on bacteria. Fungi have been hard to study – we know very little of what they can do – but we do know that they develop bioactive substances naturally, as a way to protect themselves and survive in a competitive environment. This made it logical to apply our tools in research on fungi.<br /><br />Researchers now have different paths to follow. One way of moving forward would be to further look at production of the new yanuthone compound. The Chalmers researchers have also constructed a map making it possible to compare hundreds of genes in the continuous evaluation of bioactive products with potent drugs in sight.<br /><br />How long it would take to get new antibiotics on the market is impossible to say.<br /><br />– The governments need to act. The pharmaceutical industry don’t want to spend money on new antibiotics, it’s not lucrative. This is why our leaders have to step in and, for instance, support clinical studies. Their support would make it easier to reach the market, especially for smaller companies. This could fuel production, Jens Christian Nielsen says.<br /><br />Read the <a href="" target="_blank">full article here<span></span><span style="display:inline-block"></span></a>.<br /><br /><br />Text: Mia Malmstedt<br />Photo: Martina Butorac<br />Wed, 05 Apr 2017 14:00:00 +0200;t waste the trash<p><b>​Most people can agree that it would be more sustainable to reuse materials in the trash that we throw away to make new products. Even though, it’s not that much of the waste that is being used again. What is it that makes recovering resources from waste so difficult? In the doctoral thesis ”Designing out waste: exploring barriers for material recirculation” by Isabel Ordonez Pizarro we find out what some of the common problems are when it comes to recirculating materials in society and suggestions for how to overcome them.</b></p>​Since the topic is so broad, Isabel has done several studies where she has looked at three different stages that might be needed to recirculate materials in society, and the material flow between these. The stages are production, use of products and disposal of products.<br /><br />– By comparing the results found in all these studies together, we could see that there were six main problems common for all stages. For example lack of reliable information on secondary materials and unclear responsibilities. The results gave us a better understanding of the difficulties for material recirculation in society. To be able to work in waste management, production systems or sustainable consumption, you need to be aware that these are stages inside a larger recirculation system, and that all stages need to move towards the same goal of material recirculation, Isabel says.<br /><br />To be able to reach the goal of material recirculation, Isabel has four suggestions for policy instruments and argues that designers working in the waste management branch would facilitate collaboration with production and waste sorting for users.  <br /><br />Most of the research done in this field have been about how to change the production, for example with ”designing for recycling” or by implementing leasing systems in industry that allows producers to get their products back for remanufacturing and recycling. In Isabel’s research, she chose to see if it is possible to recirculate materials that are discarded today. Starting with waste management instead of production.<br /><br />– Resource recovery from waste has been covered by the waste management branch, but not specifically with the goal of making new products. So, to look at this problem with my professional perspective as an industrial designer is something different and my results are both expected and unexpected. For example, it was expected to see that designing with waste materials is difficult to do. With all the available sustainable design methods I expected more designers to actively include ”End-of-life” considerations when they do product development. I was also surprised to learn how much recyclable or bio-degradable material is being incinerated due to a lack of waste sorting, she says.<br /><br />– In general, I think that people who are interested in circular economy or material recirculation will find my work useful. But I still think that it’s much work left to do. I would like to establish material recirculation hubs in urban areas, where local producers, secondary material providers, waste managers and makers can meet and create new ways of collaborating to enable material recovery. I also find it interesting to develop more efficient, decentralized waste management solutions and I believe that it would help users to sort their waste better, Isabel says.<br /><br />Isabel will be presenting her doctoral thesis ”<a href="">Designing out waste: exploring barriers for material recirculation</a>” on January 27 at 13.00 in Virtual Development Laboratory.<br /><br />After the defence, Isabel would like to apply for new project funding to continue doing research that may help material recirculation. She is also looking forward to finally get some time to do her own design again, with discarded material of course.<br /><br /><span><em>During her doctoral studies, Isabel have collaborated with other PhD students from Borås University, KTH and India. For some of the studies she has worked together with Stena Recycling, Semcon, the housing company Poseidon AB, the office for Sustainable Waste and Water of the City of Gothenburg and the waste management companies Envac and Renova. Her research has received funding from <a href="">Mist</a><span></span><span></span><span></span><span>ra Urban Futures</span>, Mistra Closing the Loop and ÅForsk. </em><span style="display:inline-block"></span></span><br /><br /><strong>Related Research Projects</strong><br /><a href="/en/projects/Pages/Bio-waste-to-Energy-Q-Facilitating-collection-of-bio-waste-in.aspx"><img class="ms-asset-icon ms-rtePosition-4" src="/_layouts/images/ichtm.gif" alt="" />Bio-waste to Energy – Facilitating collection of bio-waste in apartment buildings</a><br /><a href="/en/projects/Pages/Municipal-Solid-Waste-Handling---A-Design-Perspective-on-Closing-the-Resource-Loops.aspx"><img class="ms-asset-icon ms-rtePosition-4" src="/_layouts/images/ichtm.gif" alt="" />From Waste to Resources. Municipal Solid Waste Handling: A Design Perspective on Closing the Resource Loops</a><br /><br /><strong>Related articles</strong><br /><a href=""><img class="ms-asset-icon ms-rtePosition-4" src="/_layouts/images/icgen.gif" alt="" />Designing out waste</a><br /><br /><strong>Contact information</strong><br /><a href="/en/Staff/Pages/isabel-ordonez-pizarro.aspx"><img class="ms-asset-icon ms-rtePosition-4" src="/_layouts/images/ichtm.gif" alt="" />Isabel Ordonez Pizarro</a><br /><br /><em>Text: Jenny Netzler</em><br /><em>Image: Roger Langvik</em><a href=""></a><br />Fri, 13 Jan 2017 16:00:00 +0100 of steering components in trucks<p><b>​In a recent PhD project by Roza Maghsood, mathematical statistics models are used to examine how much the steering components in trucks must endure due to the customers’ behaviour.</b></p><p>​<img class="chalmersPosition-FloatRight" alt="Roza Maghsood" src="/SiteCollectionImages/Institutioner/MV/Nyheter/rozamaghsood250x.jpg" style="margin:5px" />Rozas PhD project has been a collaboration with Volvo Trucks, aiming to optimize vehicles based on customer usage. The focus has been on detecting and estimating the number of events related to steering components, such as curves and manoeuvres, to find out how much damage the steering components are exposed to and to be able to improve the design elements. </p> <p>The tests have been made with both simulated and measured real data. In general, customer vehicles have no access to measurements dedicated to durability, and using specially equipped vehicles in service is difficult and expensive. Therefore, the events have been detected by using the information available for all vehicles known as Controller Area Network (CAN) bus data. By counting the number of driving events, one can estimate the fatigue damage caused by the same kind of events.</p> <p>The results have been good and the job has been extended to estimate the number of events online as a new observation arrives without needing to store the previous observations. The proposed statistical method to estimate the number of events in the project was hidden Markov models, and in the end it could be concluded that the method works well both online and offline.</p> <p>Roza came to Gothenburg in 2009 with a master in mathematical statistics from Allameh Tabatabaei University in Iran to get a second master in financial mathematics at the University of Gothenburg. She learnt how to use mathematical statistics in finance and found the teachers and supervisors to be very good. During her second master, she got the position as PhD at this project.</p> <p>– This has been a very nice environment and I have also had good colleagues, as well as a good steering group at Volvo who really improved my knowledge about automative applications, I will miss them! But we are going to apply for money and hope that the project will continue to create knowledge that lead to more cost efficient transport vehicle specifications with high energy efficiency.</p> <p>Roza has also been teaching and is right now the main teacher of the course Mathematical statistics and discrete mathematics, for Computing Science and Engineering. She says that she loves teaching, and concludes that she is really happy that she got this position where she has got good experience for the future.<br /><br /><em>Roza Maghsood will defend her PhD thesis “Hidden Markov models for detecting steering events and valuating fatigue damage” on September 23 at 13.15 in the room Pascal, Hörsalsvägen 1. Supervisor is Igor Rychlik, co-supervisors are Pär Johannesson and Jonas Wallin.</em><br /><strong><br />Text and photo</strong>: Setta Aspström</p>Thu, 22 Sep 2016 01:50:00 +0200 versus multiplication<p><b>​The PhD thesis of Dmitrii Zhelezov belongs to the areas of combinatorial number theory and arithmetic combinatorics. Each of the five research papers has explored the sum-product phenomenon in various settings.</b></p><p><img class="chalmersPosition-FloatRight" alt="Dmitrii Zhelezov" src="/SiteCollectionImages/Institutioner/MV/Nyheter/dmitriizhelezovnyhet.jpg" style="margin:5px" />In number theory, the famous abc conjecture states that if the integer numbers <em>a</em> and <em>b</em> are composed from large powers of primes, the sum <em>c</em> is not divisible by large powers of primes. Sometimes the abc conjecture is described as “the most important problem in Diophantine analysis”. A solution was claimed three years ago by a Japanese mathematician, but no one has yet been able to understand his proof and verify it in full.</p> <p>Roughly speaking, the abc conjecture tells us that addition destroys multiplicative structure. The sum-product conjecture states that a similar phenomenon occurs in statistical sense, namely that for any finite set of real numbers, either the pairwise sums or the pairwise products of the numbers in the set form a significantly larger set. If sum-product phenomena are extended in a more general setting, one can define additive and multiplicative structures in different terms, and the questions that arise from that become completely different from each other.</p> <p>Dmitrii took his master degree in finance mathematics at Halmstad University, and when he applied for and got a free position as PhD at Chalmers it was his intention to continue in that field. However, Christer Borell who had been responsible for finance mathematics was just about to retire, and the vacancy had not yet been filled. Dmitrii had to choose something else. In high school in St Petersburg he had participated in the Mathematical Olympiad, which is very much about discrete mathematics, to which the areas of his thesis belongs. Dmitrii vividly describes in the dissertation how he knocked on Peter Hegarty’s door and asked if he could be his supervisor, though he had no idea what problems he wanted to work with.</p> <p>Discrete mathematics is a very wide research field, and in the beginning Dmitrii worked with various problems, such as percolation. One day Peter asked Dmitrii about a certain problem, which he tried to solve, but in vain. His attempts to construct a counterexample for the problem gradually led him to the essays in the thesis. Originally it seemed to be different problems, but when looking back he saw that they were all connected. Some of the essays deal with relatively new subjects and only a few people work with them right now, though it has become clear that there are many connections to classical and analytical number theory.</p> <p>– There are a lot of well-known open questions in the field, but only a few answers. To solve those questions, the right methods have yet to be invented. It is not just about hard work – if you do not come up with the right ideas, the work is futile. But step by step, we come closer to the answers.</p> <p><em>Dmitrii Zhelezov will defend his PhD thesis Additively and multiplicatively structured sets on February 26 at 13.15 in the room Pascal, Hörsalsvägen 1. Supervisor is Peter Hegarty, co-supervisor is Jeffrey Steif.</em><br /><br /><strong>Text and photo</strong>: Setta Aspström</p>Fri, 19 Feb 2016 07:40:00 +0100