DELTA. 26 22-09-2011
science
opinion please
04
How to build an eco-city During Green Building Week, a team of TU lecturers has launched a brand new book on eco-cities. The book is to help future designers and engineers to green up the urban environment. Jos Wassink
Dutch internet security fails TU Delft scientists are not surprised that the Dutch government faces major security issues on the web. They stress that there is little awareness of security issues. Every year Dutch journalists try to get their hands on the classified budget for next year. This year they received the budget in a very simple way: it was published accidentally in advance on the internet, and on a webpage that wasn’t even encrypted. This blunder launched a lively discussion about how the government fails to secure important documents. Even more troublesome were the problems involving a company called DigiNotar, which went bankrupt last week. DigiNotar provided secured certificates for the government. DigiNotar was hacked by an Iranian, who then created certificates. Iran allegedly used the certificates to spy on its own people, although this is not yet certain. Over the past couple of weeks, many people have asked themselves how it is possible that the government does not take IT security more seriously. But TU Delft scientists are not surprised. “There isn’t much awareness about security at the government level. Many people who design websites do not take security seriously enough. There aren’t enough ICT specialists in government service. And the same goes for many big companies,” says Dr Johan Pouwelse (Software Technology section, faculty of Electrical Engineering, Mathematics and Computer Science). The certificates issued by DigiNotar were being used to digitally identify websites and to encrypt traffic to and from https-websites. It is not yet known officially what went wrong, but human errors seem to have been made. “Strangely enough, it looks like employees at Diginotar had not enough awareness regarding security,” says Dr Jan van den Berg (ICT section of the faculty of Technology, Policy and Management). “But also the monitoring of the company failed tremendously. There should have been better supervision from the government. Hopefully this will change fast.” The DigiNotar scandal also affects TU Delft, as the company was the delivering party at the TU for certificates. Whoever wanted to sign and send a contract by email and encrypt a confidential email at TU Delft used DigiNotar. “We did not expect at all that security at DigiNotar was this bad, because they were being monitored. We thought they were trustworthy. It seems like all the processes inside the company were good, but human errors were made. This should not have happened. After the hack was known we sent emails to whomever used DigiNotar at the TU, informing them that their certificates could not be used anymore,” adds Alf Moens, corporate information security officer at the TU. Van den Berg also used DigiNotar: “I even taught my students how to send encrypted information by using certificates signed by DigiNotar during my classes.” According to Van den Berg, a lot of new changes should be made to make the internet safer. “We made up rules that are necessary to drive a car. One needs a driver’s license and to put seatbelts on. Otherwise, it’s not regarded safe to drive. I’m surprised that something similar doesn’t exist yet for the internet.” The freedom on the internet is great, he says, but is also too good to be true. “Everyone who uses the internet should use certificates for certain applications, to be sure that anyone who says who he or she is, really is that person. Of course this is more inconvenient, but whenever one collects a passport there are also security precautions. No one thinks that is strange, because we know why it’s important. That’s why we should start making people more aware of the necessity to secure computers that are connected to the web.” (RV)
Love them or loathe them, cities are here to stay. In 2007 half of the world’s population lived in cities and by 2050 the UN expects seventy percent of all people will be urbanites. The UN Habitat programme foresees the rise of mega- and hypercities with over twenty million inhabitants. One could regard cities as ecological monsters consuming water, energy and materials in huge amounts (forty percent of all materials extracted is used in buildings and structures), and releasing polluted water, greenhouse gases and piles of waste in return. But then again, cities are also the centres of our economy and generate new economic activities, such as shops, offices and services. ‘In this book we aim to avoid thinking of cities in terms of good or bad,’ writes editor and assistant professor Dr Ellen van Bueren (TPM). ‘Cities are there, and most of them are growing. This is something that we should take as a starting point for our attempts to make them sustainable…. The urban environment holds various keys to a more sustainable planet.’ As examples, she mentions high-density buildings to reduce land use, reusing building
The eco-city design ‘Hanging Gardens’ for the Erasmusveld quarter in The Hague. (Illustration: Arjan van Timmeren/2T atelier)
materials, making buildings energyefficient or even energy producing, and providing buildings with green roofs. There is a wealth of opportunities at hand. The large tome (429 pages) is the outcome of a collective effort of 16 authors from three faculties (Architecture; Civil Engineering and Geosciences; Technology, Policy and Management) and the research institute OTB. Titled ‘Sustainable Urban Environments’, the publication has been written as a textbook for the module ‘Sustainable Urban Environments & Infrastructures’ in the MSc programme Industrial Ecology (TU Delft in cooperation with Leiden University). “Most similar books just cover energy, water or sanitation topics,” says Van Bueren. “Other books give an overview of best practices, but these tend
to be fairly soon outdated.” So, the authors chose a different tack – the systemic approach. “What are the problems you want to address, how do you choose your system boundaries (what to include and what not) and which solutions are there on offer?” says Van Bueren. She is well aware that the urban dynamics is such that future professionals will constantly be confronted by new solutions and new challenges. This new book should help to prepare them.
Ellen van Bueren et.al., ‘Sustainable Urban Environments – an ecosystem approach’, Springer Verlag, 2012. The book was presented at the first Delft Environment Initiative Lecture, last Wednesday at BK-city.
Exploring the molecular toolkit
Molecular engine designed by Seldenthuis and Prins. (Illustration: Marijn van der Meer)
Make a nanogap, stick a molecule across and see what it does. Ferry Prins’ experiments could lead to molecular memories, more efficient solar cells and the tiniest motor ever. He is basically a chemist, although he mainly worked with physicists during his PhD project. Dr Ferry Prins just loves molecules and is excited that the latest technologies at Applied Sciences allowed him to almost put his finger onto these tiniest building blocks of chemistry. What’s more: he
did most of his experiments at room temperature. A whole lot of tricks are required to get in contact with single molecules. A 1 to 2 nanometer wide gap for example cannot be made by lithography. Instead, a current is fed through a thin platinum wire until it locally ‘evaporates’ and leaves a nanogap between the electrodes. Now try to stick a molecule across the gap – another nasty hit and miss affair, which requires patience and persistence. Prins’ patience was rewarded with the discovery of very useful molecular traits. For example, he reports the discovery of a molecular switch – a molecule able to switch between two spin states. Moreover, the iron-based poly-
mer works at room temperature and its spin state is externally readable. That sounds like a promising candidate for yet smaller memory devices. Prins also used lead-selenide quantumdots as photodetectors. Resting between two electrodes only 5 nanometers apart, the quantumdots readily pass on any electrons freed by incident photons. The electronic efficiency is much higher than in traditional solar devices, but in the present configuration no external current is generated. Prins’ successors are busy inventing solutions for that. Lastly, Prins also designed a molecule that can serve as a rotor in a molecular engine. At two extremes the (flat) molecule has two rings, which should bind to two gold electrodes. The other two extremes of the molecules are electrically charged, which makes the molecule sensitive to the electric fields. Prins, and his colleague Jos Seldenthuis (MSc), hope to demonstrate that the application of an alternating electric field to an adjacent electrode will nudge the molecular engine into rotation. (JW)
Ferry Prins, 'Molecular functionality in nanoelectronic devices', 16 September 2011, PhD supervisor: Professor Herre van der Zant (AS)