Multichannel sparse recovery of complex-valued signals using Huber's criterion

In this paper, we generalize Huber's criterion to multichannel sparse recovery problem of complex-valued measurements where the objective is to find good recovery of jointly sparse unknown signal vectors from the given multiple measurement vectors which are different linear combinations of the same known elementary vectors. This requires careful characterization of robust complex-valued loss functions as well as Huber's criterion function for the multivariate sparse regression problem. We devise a greedy algorithm based on simultaneous normalized iterative hard thresholding (SNIHT) algorithm. Unlike the conventional SNIHT method, our algorithm, referred to as HUB-SNIHT, is robust under heavy-tailed non-Gaussian noise conditions, yet has a negligible performance loss compared to SNIHT under Gaussian noise. Usefulness of the method is illustrated in source localization application with sensor arrays.Comment: To appear in CoSeRa'15 (Pisa, Italy, June 16-19, 2015). arXiv admin note: text overlap with arXiv:1502.0244

On asymptotics of ICA estimators and their performance indices

Independent component analysis (ICA) has become a popular multivariate analysis and signal processing technique with diverse applications. This paper is targeted at discussing theoretical large sample properties of ICA unmixing matrix functionals. We provide a formal definition of unmixing matrix functional and consider two popular estimators in detail: the family based on two scatter matrices with the independence property (e.g., FOBI estimator) and the family of deflation-based fastICA estimators. The limiting behavior of the corresponding estimates is discussed and the asymptotic normality of the deflation-based fastICA estimate is proven under general assumptions. Furthermore, properties of several performance indices commonly used for comparison of different unmixing matrix estimates are discussed and a new performance index is proposed. The proposed index fullfills three desirable features which promote its use in practice and distinguish it from others. Namely, the index possesses an easy interpretation, is fast to compute and its asymptotic properties can be inferred from asymptotics of the unmixing matrix estimate. We illustrate the derived asymptotical results and the use of the proposed index with a small simulation study

Uskottavaa dokumenttielokuvaa rakentamassa : Tarkastelun kohteena dokumentaarinen Shoot me! -elokuva

Opinnäytetyöni kirjallisessa osassa pyrin selvittämään vaikuttamisen keinoja, joita tekijä käyttää hyödyksi dokumenttielokuvan teon eri vaiheissa. Tämä on samalla kirjallisen työni näkökulma. Tutkimuskohteena käytin ohjaamaani Shoot me! -dokumenttielokuvaa, jonka myös kuvasin ja leikkasin. Dokumenttielokuva kertoo luovuudesta ja sen uhista. Dokumentin päähenkilönä toimii valokuvaaja ja graafinen suunnittelija Harri Tarvainen. Shoot me! -dokumentti valmistui keväällä 2010. Lähdekirjallisuutena käytin dokumenttielokuvien tekemisestä ja moodeista kertovaa kirjallisuutta, jota rinnastin oman dokumenttini pohdintaan ja tutkimiseen. Tutkin dokumenttielokuvan tekemisen eri vaiheita ja pohdin, mitä eri vaikuttamisen keinoja tekijällä on käytössään. Tutkimuksessa selvisi, että vaikuttamisen kannalta on tärkeä tehdä hyvä ennakkosuunnittelu, onnistua kuvauksissa ja luottaa omaan intuitioon jälkituotantovaiheessa.My bachelor’s thesis consists of two parts. The work part is a documentary film called Shoot me!. In my analytical part I aim to investigate different ways of influencing when making a documentary movie from the director’s point of view. My study focuses on a documentary film called Shoot me! which I directed, filmed and edited. This documentary is about creativity, but also and the threats of creativity. The main character in the documentary is a photographer and graphical designer Harri Tar-vainen. The documentary film Shoot me! was completed in the spring of 2010. The literature I used for my work is about making documentary films and modes, which I assimilated with the information into my documentary. I studied different stages of making documentary films as well as discussed the directors’ ways of influencing in the production of documentary films. In my study I found that when making documentary films that aim to influence it is im-portant to make a good plan, succeed in the filming stage and trust your own intuition in the post-production stage