Dr Bogdan Roman
I'm a Senior Researcher at the Maths department in the Centre for Mathematical Imaging in Healthcare, a Research Fellow at the Computer Laboratory department, and Director of Studies for Computer Science at Queens' College. I also chair the Computer Science Admissions Test (CSAT), which I initially designed.
Email:
Office: F2.05
News

Our proposal "IMPROVED SPATIAL RESOLUTION AND TARGETED SAMPLING IN MRI" by Bogdan Roman, Martin J Graves, Anders Hansen, David J Lomas was selected by the University after an internal competition as the University's nomination for the prestigious Rosetrees Interdisciplinary Prize 2016 (250,000 GBP). This is work done in collaboration with the Radiology department and Cambridge University Hospitals on MRI, using General Electric 1.5T and 3T scanners. It showcases visible resolution improvement and shorter acquisition time simultaneously in a clinical setting. This can impact both clinical and research applications, allowing for improved morphological and functional imaging with the potential for earlier and improved diagnosis and outcomes. The work extends the practical validation done by Siemens in 2014 of our compressed sensing research.
The Rosetrees Trust was established in 1987 to fund lifechanging medical research. The Rosetrees Interdisciplinary Prize is an annual award for innovative and impactful interdisciplinary research on biomedical problems.

Siemens validated in practice, using a modified MRI machine, the asymptotic sparsity, asymptotic incoherence and high resolution concepts introduced by our work (see Breaking the coherence barrier: A new theory for compressed sensing and also On asymptotic structure in compressed sensing). From their results and conclusion:
“The image resolution has been greatly improved [...]. Current results practically demonstrated that it is possible to break the coherence barrier by increasing the spatial resolution in MR acquisitions. This likewise implies that the full potential of the compressed sensing is unleashed only if asymptotic sparsity and asymptotic incoherence is achieved.”
Their work Novel Sampling Strategies for Sparse MR Image Reconstruction was published in May 2014 in the Proceedings of the International Society for Magnetic Resonance in Medicine. The effects and benefits of these concepts are found in our work On asymptotic structure in compressed sensing, which also includes a large number of example experiments.
Research, Teaching
Colecture the Part III course on Sampling and Compressed Sensing. See my CL homepage for my teaching/supervising for compsci/engineering.
Interested in compressed sensing, signal processing, sampling theory, inverse problems, computational mathematics. See my CL homepage for my research on wireless comms.
Admissions, Exercises
 I coordinate the Computer Science Admissions Test (CSAT), which is supposed to be primarily nontrivial maths. It's taken by all CompSci undergraduate applicants to Cambridge.
 Probability questions and puzzles. These are short, yet not all trivial. I also use them in my teaching.
I welcome alternative solutions, extensions or new questions for any of the above.
Code
 (Very) Fast C++ MEX Hadamard (WalshHadamard) transform with support for sequency and natural
ordering, multicore/multicpu and also complex values. Orders of magnitude faster than
Matlab's fwht() function.
Download v1.3, Oct 2014. Includes 64bit binaries for Linux, MacOSX and Windows, and Matlab wrappers for 1D and 2D transforms, unitary and nonunitary.  Compiling MEX files directly from Matlab seamlessly under Windows using GCC (MinGW64).
This should normally work with most C/C++ MEX files that work under Linux. You also won't
need to carry or distribute the std runtime .DLLs from MingW/Cygwin.
Download this mexopts.bat file and place it in %USERPROFILE%\AppData\Roaming\Mathworks\MATLAB\R2014a\. See more instructions and details inside the downloaded mexopts.bat file (see also this StackExchange answer).  MacOH. Automated tool for stress testing Mac machines to reveal throttling or overheating. It downloads all needed tools, starts benchmarks, monitors CPU temperature and frequency, and plots them versus time (sample output). First created as a personal test tool. It can do CPU and GPU tests (Prime95, x264, GpuTest, user defined).
Publications
 B. Roman, B. Adcock, R. Calderbank, M. Graves, D. Nietlispach, M. Bostock, I. CalvoAlmazan, A. Hansen, Exploiting asymptotic structure to enhance resolution in undersampled physical imaging, 2016 (in submission)
 B. Adcock, A. C. Hansen, C. Poon, B. Roman, Breaking the coherence barrier: A new theory for compressed sensing, Sigma, 2016 (accepted)
 B. Roman, A. Bastounis, B. Adcock, A. Hansen, On fundamentals of models and sampling in compressed sensing, 2016 (in submission)
 B. Roman, B. Adcock, A. Hansen, On asymptotic structure in compressed sensing, arXiv:1406.4178, 2014
 B. Adcock, A. Hansen, B. Roman, Compressed sensing with local structure: Theory, applications and benefits , IEEE Samp. Theory and Appl., SampTA'15, 2015
 B. Adcock, A. C. Hansen, B. Roman, The quest for optimal sampling: Computationally efficient, structureexploiting measurements for compressed sensing, Book: Compressed Sensing and Its Applications, Springer, 2015
 B. Adcock, A. C. Hansen, B. Roman, A note on compressed sensing of structured sparse wavelet coefficients from subsampled Fourier measurements, arXiv:1403.6541, 2014
 B. Adcock, A. C. Hansen, B. Roman, G. Teschke, Generalized sampling: stable reconstructions, inverse problems and compressed sensing over the continuum, Book series: Advances in Imaging and Electron Physics, vol. 182, Elsevier, 2014
 B. Adcock, A. C. Hansen, C. Poon, B. Roman, Breaking the coherence barrier: asymptotic incoherence and asymptotic sparsity in compressed sensing, IEEE Samp. Theory and Appl., SampTA'13, 2013
 S. Akoush, R. Sohan, B. Roman, A. Rice, A. Hopper, Activity Based Sector Synchronisation: Efficient Transfer of DiskState For WAN Live Migration, IEEE Modeling, Analysis and Simulation of Computer and Telecommunication Systems, MASCOTS'11, 2011
 B. Roman, I. Wassell, I. Chatzigeorgiou, CrossLayer Wireless Access Control Using MultiCarrier Burst Contention, IEEE Journal on Selected Areas in Communications, vol. 29, no. 1, pp. 113128, 2011
 B. Roman, I. Chatzigeorgiou, I. Wassell, F. Stajano, Evaluation of MultiCarrier Burst Contention and IEEE 802.11 with Fading During Channel Sensing, IEEE Personal Indoor Mobile Radio Communications, PIMRC'09, 2009
 B. Roman, F. Stajano, I. Wassell, D. Cottingham, MultiCarrier Burst Contention (MCBC): Scalable Medium Access Control for Wireless Networks, IEEE Wireless Communications and Networking Conference, WCNC'08, 2008
 B. Roman, F. Stajano, Scalable Medium Access Control, Microsoft Research Workshop 2007 (won 2nd place), Cambridge, UK, 2007
PhD Thesis:
B. Roman, Scalable CrossLayer Wireless Medium Access Control,
University of Cambridge, Computer Laboratory, 2011