7,658 research outputs found
Spying the World from your Laptop -- Identifying and Profiling Content Providers and Big Downloaders in BitTorrent
This paper presents a set of exploits an adversary can use to continuously
spy on most BitTorrent users of the Internet from a single machine and for a
long period of time. Using these exploits for a period of 103 days, we
collected 148 million IPs downloading 2 billion copies of contents. We identify
the IP address of the content providers for 70% of the BitTorrent contents we
spied on. We show that a few content providers inject most contents into
BitTorrent and that those content providers are located in foreign data
centers. We also show that an adversary can compromise the privacy of any peer
in BitTorrent and identify the big downloaders that we define as the peers who
subscribe to a large number of contents. This infringement on users' privacy
poses a significant impediment to the legal adoption of BitTorrent
Frequency tunable antenna for digital video broadcasting handheld application
International audienceIn this paper, we present a frequency tunable antenna suitable for Digital Video Broadcasting Handheld applications. Due to the narrow operating frequency band of the antenna derived from a monopole coupled loop antenna, a tuning system has been proposed to sweep the narrow band on a large frequency range in order to cover the DVB-H frequency bandwidth [470-702] MHz. We provide results of this antenna mounted on a circuit board simulating a terminal handset
Phase boundary between Na-Si clathrates of structures I and II at high pressures and high temperatures
Understanding the covalent clathrate formation is a crucial point for the
design of new superhard materials with intrinsic coupling of superhardness and
metallic conductivity. Silicon clathrates have the archetype structures that
can serve an existant model compounds for superhard clathrate frameworks
"Si-B", "Si-C", "B-C" and "C" with intercalated atoms (e.g. alkali metals or
even halogenes) that can assure the metalic properties. Here we report the in
situ and ex situ studies of high-pressure formation and stability of clathrates
Na8Si46 (structure I) and Na24+xSi136 (structure II). Experiments have been
performed using standard Paris-Edinburgh cells (opposite anvils) up to 6 GPa
and 1500 K. We have established that chemical interactions in Na-Si system and
transition between two structures of clathrates occur at temperatures below
silicon melting. The strong sensitivity of crystallization products to the
sodium concentration have been observed. A tentative diagram of clathrate
transformations has been proposed. At least up to ~6 GPa, Na24+xSi136
(structure II) is stable at lower temperatures as compared to Na8Si46
(structure I)
Support Vector Machine in Prediction of Building Energy Demand Using Pseudo Dynamic Approach
Building's energy consumption prediction is a major concern in the recent
years and many efforts have been achieved in order to improve the energy
management of buildings. In particular, the prediction of energy consumption in
building is essential for the energy operator to build an optimal operating
strategy, which could be integrated to building's energy management system
(BEMS). This paper proposes a prediction model for building energy consumption
using support vector machine (SVM). Data-driven model, for instance, SVM is
very sensitive to the selection of training data. Thus the relevant days data
selection method based on Dynamic Time Warping is used to train SVM model. In
addition, to encompass thermal inertia of building, pseudo dynamic model is
applied since it takes into account information of transition of energy
consumption effects and occupancy profile. Relevant days data selection and
whole training data model is applied to the case studies of Ecole des Mines de
Nantes, France Office building. The results showed that support vector machine
based on relevant data selection method is able to predict the energy
consumption of building with a high accuracy in compare to whole data training.
In addition, relevant data selection method is computationally cheaper (around
8 minute training time) in contrast to whole data training (around 31 hour for
weekend and 116 hour for working days) and reveals realistic control
implementation for online system as well.Comment: Proceedings of ECOS 2015-The 28th International Conference on
Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy
Systems , Jun 2015, Pau, Franc
Compromising Tor Anonymity Exploiting P2P Information Leakage
Privacy of users in P2P networks goes far beyond their current usage and is a
fundamental requirement to the adoption of P2P protocols for legal usage. In a
climate of cold war between these users and anti-piracy groups, more and more
users are moving to anonymizing networks in an attempt to hide their identity.
However, when not designed to protect users information, a P2P protocol would
leak information that may compromise the identity of its users. In this paper,
we first present three attacks targeting BitTorrent users on top of Tor that
reveal their real IP addresses. In a second step, we analyze the Tor usage by
BitTorrent users and compare it to its usage outside of Tor. Finally, we depict
the risks induced by this de-anonymization and show that users' privacy
violation goes beyond BitTorrent traffic and contaminates other protocols such
as HTTP
De-anonymizing BitTorrent Users on Tor
Some BitTorrent users are running BitTorrent on top of Tor to preserve their
privacy. In this extended abstract, we discuss three different attacks to
reveal the IP address of BitTorrent users on top of Tor. In addition, we
exploit the multiplexing of streams from different applications into the same
circuit to link non-BitTorrent applications to revealed IP addresses.Comment: Poster accepted at the 7th USENIX Symposium on Network Design and
Implementation (NSDI '10), San Jose, CA : United States (2010
One Bad Apple Spoils the Bunch: Exploiting P2P Applications to Trace and Profile Tor Users
Tor is a popular low-latency anonymity network. However, Tor does not protect
against the exploitation of an insecure application to reveal the IP address
of, or trace, a TCP stream. In addition, because of the linkability of Tor
streams sent together over a single circuit, tracing one stream sent over a
circuit traces them all. Surprisingly, it is unknown whether this linkability
allows in practice to trace a significant number of streams originating from
secure (i.e., proxied) applications. In this paper, we show that linkability
allows us to trace 193% of additional streams, including 27% of HTTP streams
possibly originating from "secure" browsers. In particular, we traced 9% of Tor
streams carried by our instrumented exit nodes. Using BitTorrent as the
insecure application, we design two attacks tracing BitTorrent users on Tor. We
run these attacks in the wild for 23 days and reveal 10,000 IP addresses of Tor
users. Using these IP addresses, we then profile not only the BitTorrent
downloads but also the websites visited per country of origin of Tor users. We
show that BitTorrent users on Tor are over-represented in some countries as
compared to BitTorrent users outside of Tor. By analyzing the type of content
downloaded, we then explain the observed behaviors by the higher concentration
of pornographic content downloaded at the scale of a country. Finally, we
present results suggesting the existence of an underground BitTorrent ecosystem
on Tor
ORGANIC FARMING IS IT A SUSTAINABLE AGRICULTURE ? DEVELOPMENT ISSUES FOR SUSTAINABLE ORGANIC FARMING IN MIDI-PYRENEES REGION
N° ISBN - 978-2-7380-1284-5International audienceBy its strong development experienced last fifteen years, organic farming has gain both institutional and professional recognitions. It is well out of its traditional marginal status and production of niche, and to become a serious and promising way of agricultural development in line with the expectations of society. But questions about the sustainability of this mode of production are still raised. The aim of this paper is to analyze the recent dynamics of organic farms, in Midi- Pyrenees region, in order to identify the main patterns of evolution of these farms and to identify priority issues of development of these farms in sustainability perspective. The methodological approach, based on systemic thinking, combines a quantitative method applied to all organic farms in the Midi-Pyrenees region, and another more qualitative and focused on specific topics on a small sample of organic farms. Results show a diversity of organic farms due to the nature of their production system and farm size. Tree trajectories of farms have been identified and analyzed. These trajectories highlight the importance of changes operated bay farmers and the main drivers of change. They depend on the level of intensification of farms before the conversion. Development issues mainly concern the economic and social dimensions of organic farming. Discussion of trajectories of farms gives some insights on the evolution of organic farming last years
Design of multimedia processor based on metric computation
Media-processing applications, such as signal processing, 2D and 3D graphics
rendering, and image compression, are the dominant workloads in many embedded
systems today. The real-time constraints of those media applications have
taxing demands on today's processor performances with low cost, low power and
reduced design delay. To satisfy those challenges, a fast and efficient
strategy consists in upgrading a low cost general purpose processor core. This
approach is based on the personalization of a general RISC processor core
according the target multimedia application requirements. Thus, if the extra
cost is justified, the general purpose processor GPP core can be enforced with
instruction level coprocessors, coarse grain dedicated hardware, ad hoc
memories or new GPP cores. In this way the final design solution is tailored to
the application requirements. The proposed approach is based on three main
steps: the first one is the analysis of the targeted application using
efficient metrics. The second step is the selection of the appropriate
architecture template according to the first step results and recommendations.
The third step is the architecture generation. This approach is experimented
using various image and video algorithms showing its feasibility
- …