Média | EPFL Graph Search

thumb|Récepteur radio de 1935 (la radio a été inventée tout au début du et s'est développée à partir du milieu des années 1930). Le terme média désigne tout moyen de distribution, de diffusion ou de communication interpersonnelle, de masse ou de groupe, d'œuvres, de documents, ou de messages écrits, visuels, sonores ou audiovisuels (comme la radio, la télévision, le cinéma, Internet, la presse, les télécommunications, etc.). Ce terme est souvent utilisé comme l'abréviation du terme anglais mass-media ou médias de masse en français. L'expression médias de masse désigne les médias qui ont acquis une diffusion à grande échelle pour répondre rapidement à une demande d'information d'un public vaste, complétée dans de nombreux cas par une demande de distraction. La plupart des entreprises dites de média emploient des journalistes et des animateurs de divertissement. Ils recueillent dans un premier temps des informations auprès de sources d'information, en leur assurant la protection des s

Computational Shifts in Theatrical Space

Andrew James Sempere

This dissertation describes a set of research projects that were conducted between 2012 and 2014 in order to answer the question how do computational ideas alter our understanding of place? Each project was produced in the context of the performing arts and included plays, dance performances and film and installation work. For each project new software and hardware systems were created as a means of exploring different types of mediated communication. These systems include a scalable depth-camera based tracking system for performance on stage, a tool for manipulation of live-streamed video incorporated into stage performance, a method of tracking biometric data of performers live during the performance and a game-engine for creating interactive environments. Collectively these experiments establish a framework for the discussion of the nature of the shifts caused by applying computational ideas to space. Finally, the results lay the foundation for further theoretical work concerning the creation of cultural artifacts that exist somewhere between the material and immaterial, the influence of computation on the nature of modeling, and the impact of ubiquitous computing on contemporary notions of performance and play.

EPFL2015

Digital model-making and the encoding of design intent

Nathaniel Zuelzke

Across many generations, including the digitally naïve and savvy, digital technologies introduce something other to the design process. This other quality ranges from inaccessibility to facile but opaque production of complexity, yet in all cases has obscured the recognition of authorial control. Fundamentally, my research interrogates this loss of control, or confusion of agency. Using the architectural model as a site of inquiry, I seek out sources of authorial control in digital design and ultimately speculate productive forms of digital agency for architecture. Digital models should be understood as continuing the legacy of architectural models rather than as a novel product of technology. As a mediator of communication, all models represent in increasing levels of abstraction. Understood literally, models mediate as images. In the formalization of underlying structure, models mediate as diagrams. Formulating structure as abstract logic, models mediate as mathematics. Digital models continue to mediate in these manners, but the nature of digital media places a new emphasis on the precise, computable definition of all of these roles. The digital process allows an author to construct a creative dialogue with a model. In this way, models are tools which operate on patterns of thought by creating feedback loops in the model- author dialogue. Formalized as the return of output back to a process as input, feedback is a mechanism which may structure both architectural form and the design decision-making process itself. In complex natural systems, feedback explains the formation of organizational patterns. In cybernetics, feedback explains the auto-regulation of an organized system. All forms of feedback can be understood as the cyclical communication of information. As such, processes of transmission and translation play a crucial role in the conveyance of information from source to receiver and back. Applied to digital model-making, feedback becomes an active decision-making mechanism, allowing an author to construct an apparatus to aid evaluation of work-in-progress and definition of increasingly specific intents. Appropriating the techno-industrial concept of design intent and citing the computational mathematical basis of digital models, I speculate the existence of a non-metaphorical solution space which can be instrumentalized by digital designers. The formalized yet iteratively changing set of possible solutions to an interpreted design problem is termed “intention space.” Computational codification of design intent makes mathematical descriptions of a digital model accessible and affords the possibility for a directed search thorough the model’s highly-structured intention space. Intention space demystifies the digital design process enabling architects to directly manipulate digital media both intuitively and deliberately. The idea of intention space is explicitly contrasted with two prevailing theories of control in digital methods: authorless design and split agency. Unlike these assertions, the encoding of design intent through mechanisms of constructed feedback and visualized as intention space proffers digital technologies as uniquely enabling instruments within the creative process.

EPFL2012

Coding for Communications and Secrecy

Mani Bastaniparizi

Shannon, in his landmark 1948 paper, developed a framework for characterizing the fundamental limits of information transmission. Among other results, he showed that reliable communication over a channel is possible at any rate below its capacity. In 2008, Arikan discovered polar codes; the only class of explicitly constructed low-complexity codes that achieve the capacity of any binary-input memoryless symmetric-output channel. Arikan's polar transform turns independent copies of a noisy channel into a collection of synthetic almost-noiseless and almost-useless channels. Polar codes are realized by sending data bits over the almost-noiseless channels and recovering them by using a low-complexity successive-cancellation (SC) decoder, at the receiver. In the first part of this thesis, we study polar codes for communications. When the underlying channel is an erasure channel, we show that almost all correlation coefficients between the erasure events of the synthetic channels decay rapidly. Hence, the sum of the erasure probabilities of the information-carrying channels is a tight estimate of the block-error probability of polar codes when used for communication over the erasure channel. We study SC list (SCL) decoding, a method for boosting the performance of short polar codes. We prove that the method has a numerically stable formulation in log-likelihood ratios. In hardware, this formulation increases the decoding throughput by 53% and reduces the decoder's size about 33%. We present empirical results on the trade-off between the length of the CRC and the performance gains in a CRC-aided version of the list decoder. We also make numerical comparisons of the performance of long polar codes under SC decoding with that of short polar codes under SCL decoding. Shannon's framework also quantifies the secrecy of communications. Wyner, in 1975, proposed a model for communications in the presence of an eavesdropper. It was shown that, at rates below the secrecy capacity, there exist reliable communication schemes in which the amount of information leaked to the eavesdropper decays exponentially in the block-length of the code. In the second part of this thesis, we study the rate of this decay. We derive the exact exponential decay rate of the ensemble-average of the information leaked to the eavesdropper in Wyner's model when a randomly constructed code is used for secure communications. For codes sampled from the ensemble of i.i.d. random codes, we show that the previously known lower bound to the exponent is exact. Our ensemble-optimal exponent for random constant-composition codes improves the lower bound extant in the literature. Finally, we show that random linear codes have the same secrecy power as i.i.d. random codes. The key to securing messages against an eavesdropper is to exploit the randomness of her communication channel so that the statistics of her observation resembles that of a pure noise process for any sent message. We study the effect of feedback on this approximation and show that it does not reduce the minimum entropy rate required to approximate a given process. However, we give examples where variable-length schemes achieve much larger exponents in this approximation in the presence of feedback than the exponents in systems without feedback. Upper-bounding the best exponent that block codes attain, we conclude that variable-length coding is necessary for achieving the improved exponents.

EPFL2017