Red Ring of Death | EPFL Graph Search

vignette|upright=1.1|Le Red Ring of Death sur une console de jeu Xbox 360. Le Red Ring of Death (abrégé en RRoD ; littéralement « Anneau rouge de la mort » en français) est une panne critique affectant les consoles de jeux vidéo Xbox et Xbox 360 conçues par Microsoft qui se manifeste par l'allumage en rouge du voyant lumineux de mise sous tension de la machine. Le terme a été créé pour trouver un équivalent au Yellow Light of Death de la PlayStation 3, lui-même inspiré de l'écran bleu de la mort que l'on connaît sur le système d'exploitation Windows du même Microsoft. Effets du Red Ring of Death vignette|upright=1.3|Image montrant les différents codes d'erreur de la console Xbox 360 originale. L'apparition du Red Ring of Death signifie que l'utilisateur final ne peut normalement pas espérer faire fonctionner à nouveau la console par ses propres moyens et doit s'en remettre au service après-vente du fabricant. Il existe cependant des procédures permettant, dans certains

Les mathématiques financières robustes, le maritime et les FFA

Jérôme Reboulleau

Powerful mathematical tools have been developed for trading in stocks and bonds, but other markets that are equally important for the globalized world have to some extent been neglected. We decided to study the shipping market as an new area of development in mathematical finance. The market in shipping derivatives (FFA and FOSVA) has only been developed after 2000 and now exhibits impressive growth. Financial actors have entered the field, but it is still largely undiscovered by institutional investors. The first part of the work was to identify the characteristics of the market in shipping, i.e. the segmentation and the volatility. Because the shipping business is old-fashioned, even the leading actors on the world stage (ship owners and banks) are using macro-economic models to forecast the rates. If the macro-economic models are logical and make sense, they fail to predict. For example, the factor port congestion has been much cited during the last few years, but it is clearly very difficult to control and is simply an indicator of traffic. From our own experience it appears that most ship owners are in fact market driven and rather bad at anticipating trends. Due to their ability to capture large moves, we chose to consider Lévy processes for the underlying price process. Compared with the macro-economic approach, the main advantage is the uniform and systematic structure this imposed on the models. We get in each case a favorable result for our technology and a gain in forecasting accuracy of around 10% depending on the maturity. The global distribution is more effectively modelled and the tails of the distribution are particularly well represented. This model can be used to forecast the market but also to evaluate the risk, for example, by computing the VaR. An important limitation is the non-robustness in the estimation of the Lévy processes. The use of robust estimators reinforces the information obtained from the observed data. Because maximum likelihood estimation is not easy to compute with complex processes, we only consider some very general robust score functions to manage the technical problems. Two new class of robust estimators are suggested. These are based on the work of F. Hampel ([29]) and P. Huber ([30]) using influence functions. The main idea is to bound the maximum likelihood score function. By doing this a bias is created in the parameters estimation, which can be corrected by using a modification of the following type and as proposed by F. Hampel. The procedure for finding a robust estimating equation is thus decomposed into two consecutive steps : Subtract the bias correction and then Bound the score function. In the case of complex Lévy processes, the bias correction is difficult to compute and generally unknown. We have developed a pragmatic solution by inverting the Hampel's procedure. Bound the score function and then Correct for the bias. The price is a loss of the theoretical properties of our estimators, besides the procedure converges to maximum likelihood estimate. A second solution to for achieving robust estimation is presented. It considers the limiting case when the upper and lower bounds tend to zero and leads to B-robust estimators. Because of the complexity of the Lévy distributions, this leads to identification problems.

EPFL2008

Revisiting the Pohang Induced Earthquake

Tristan Liardon

The failure of the Enhanced Geothermal System project of Pohang is a valuable case for understanding better the complex mechanisms at play, as such understanding is crucial to the development of geothermal energy. We summarized analysis of the available data and recent simulations results and discuss their findings and limitations. Poroelastic finite elements simulations were attempted, but failed due to technical problems that were unsolvable during the duration of this problem.

2021

Teaching an Ethnographic Approach to Requirements Elicitation in an Enterprise Architecture Course

Julie Lang, Yasmina Naim, Gil Regev, Alain Wegmann

Requirements elicitation is an important part of information systems development. It is often performed as a technical task, but from a close look it is mainly a social activity. The main work consists of interacting with stake-holders in order to understand their work practices and how these would change with the introduction of a new IT system. Engineers are often not trained in the necessary social skills. Most elicitation techniques focus on the technical issues rather than the social issues. In this paper we describe a trans-disciplinary col-laboration in which students of social sciences help to explain the ethnographic approach to Master’s students in an Enterprise Architecture course taught in an engineering school.

CEUR Workshop Proceedings2015

Les mathématiques financières robustes, le maritime et les FFA

Jérôme Reboulleau

EPFL2008