In my research work, I often find it difficult to get datasets for X-ray CT for method validation, neither simulated and real data. Of course, there's the classic Shepp-Logan phantom, but in many cases it would save a lot of work to download datasets to test one's methods. As for my knowledge, there is no broad […]
Category: physics
Paula Eerola, coordinating Finnish physics research at CERN
I publish here my interview to Paula Eerola, which was originally published on the blog of our local network of women in science, Kumpula Women's Network. Since January 1st, 2016, the Helsinki Institute of Physics has a new appointed director, Prof. Paula Eerola from University of Helsinki. Paula is the 4th director of the Institute since its start of […]
Mathematicians Go Hollywood
Did you know that in 2008 a mathematician won an Academy Award? Do you know how to model realistic hair for animation movies or a bomb deflagrating for an action movie? Or you simply need some effective active contour segmentation method? All these questions have in common an effective, yet intuitive, mathematical framework: level set […]
4D tomography: walkthrough of my project - part 3
Here comes the final part of the walkthrough of my current project on dynamic sparse tomography (see also part 1 and part 2). In the previous post I left the question of the choice of the cut-off function hanging. In a classical level set method, would be the Heaviside step function. The Heaviside function is […]
4D tomography: walkthrough of my project - part 2
After talking about motivation (see the first part and then part 3), I will now go into details with the mathematics foundations of the project. The novel tomography reconstruction algorithm I am contributing developing is based on a level set method approach. Level set methods A level set method is an elaborate, yet geometrically intuitive, framework to deal […]
4D tomography: walkthrough of my project - part 1
Last month the greatest event in Inverse Problems ever took place in Helsinki: the Applied Inverse Problems 2015 conference. In addition, I gave my first technical presentation at the 4D tomography minisymposium (find the slides here). I take the chance to write a series of posts as a walkthrough of my project and its current state. The project When […]
Sofia Kovalevskaya: the girl who wanted something else
After several days of no writing, I will make up by publishing some edited notes that I used during one guest lecture this week. This is a short bio of a brilliant female mathematicians who lived about 150 years ago. Her story is an example of personal determination and brilliant mind, but also can make […]
The "Helsinki walnut" dataset
Our research group has made an open access dataset for image reconstruction available at the following link: www.fips.fi/dataset.php The measurement data was collected and documented by K. Hämäläinen, L. Harhanen, A. Kallonen, A. Kujanpää, E. Niemi and S. Siltanen. Our group used the walnut data for testing several tomographic reconstruction algorithms, as you can see […]
Creating a voice: a challenging inverse problem (part 2)
(a continuation of this previous post) In this post, I will describe how the human voice is produced and why this is useful to the approach of the Inverse Problems Group at University of Helsinki. Our voice is produced by air flowing from our lungs through our vocal folds and vocal tract. Vocal folds - commonly known as […]
Ettore Majorana: is the mystery solved?
A breaking piece of news appeared today on one Italian national newspaper: there is proof of Ettore Majorana being in Venezuela in the 1950s. Maybe you have never heard of him, but Majorana was a gifted Italian physicist who had produced great theoretical results in particle physics and quantum mechanics. The discovery of neutrinos was bestowed […]