140 research outputs found
Enforcing email addresses privacy using tokens
We propose a system which allows users to monitor how their email addresses are used and how they spread over the Internet. This protects the privacy of the user and can reduce the spam phenomenon. Our solution does not require changes to the email infrastructure, can be set up by the end user on an individual basis and is compatible with any email client as long as emails are centralized on a server (e.g. an IMAP server). Nevertheless, it requires that people use email messaging quite differentl
Low Latency High Bandwidth Anonymous Overlay Network with Anonymous Routing
Most existing anonymous networks focus on providing strong anonymity for the price of having lower bandwidth, higher latency and degraded usability when compared with the conventional use of the Internet. They also often anonymize only a few specific applications.
In this paper, we propose a new approach of constructing an anonymous network. The network consists of an overlay network, which provides anonymity to all applications running on top of it, and a routing protocol, which can be considered as an anonymized version of path vector routing. The protocol preserves the high performance characteristics of the path vector routing and also has the added advantage of hiding the overlay network topology. Our simulation results show that the expected latency of our approach is 50% better than that of existing systems.
Besides the new anonymous routing protocol, this paper aims to provide the general overview of this new anonymous overlay network which may serve as the input for further research
Ontology for Future-robust Product Portfolio Evolution: A Basis for the Development of Models and Methods
The future-robust evolution of product portfolios is a key challenge for manufacturing companies. It requires the integration of strategic product planning and the understanding that products are developed in generations based on references following the SGE - System Generation Engineering theory. There is, though, a lack of consistent terminology that unites these topics and makes their concepts consistent. Their terms are used differently across industries, institutions, and companies. The resulting miscommunication leads to a loss of efficiency. Hence, a structured, interrelated terminology is needed. The paper contributes an ontology that delivers a unifying basis for the development of models and methods
Is the far border of the Local Void expanding?
According to models of evolution in the hierarchical structure formation
scenarios, voids of galaxies are expected to expand. The Local Void (LV) is the
closest large void, and it provides a unique opportunity to test
observationally such an expansion. It has been found that the Local Group,
which is on the border of the LV, is running away from the void center at ~260
km/s. In this study we investigate the motion of the galaxies at the far-side
border of the LV to examine the presence of a possible expansion. We selected
late-type, edge-on spiral galaxies with radial velocities between 3000 km/s and
5000 km/s, and carried out HI 21 cm line and H-band imaging observations. The
near-infrared Tully-Fisher relation was calibrated with a large sample of
galaxies and carefully corrected for Malmquist bias. It was used to compute the
distances and the peculiar velocities of the LV sample galaxies. Among the 36
sample LV galaxies with good quality HI line width measurements, only 15
galaxies were selected for measuring their distances and peculiar velocities,
in order to avoid the effect of Malmquist bias. The average peculiar velocity
of these 15 galaxies is found to be -419+208-251 km/s, which is not
significantly different from zero. Due to the intrinsically large scatter of
Tully-Fisher relation, we cannot conclude whether there is a systematic motion
against the center of the LV for the galaxies at the far-side boundary of the
void. However, our result is consistent with the hypothesis that those galaxies
at the far-side boundary have an average velocity of ~260 km/s equivalent to
what is found at the position of the Local Group.Comment: 15 pages, 6 figures, and 4 tables. Accepted for publication in A&
DolphinAtack: Inaudible Voice Commands
Speech recognition (SR) systems such as Siri or Google Now have become an
increasingly popular human-computer interaction method, and have turned various
systems into voice controllable systems(VCS). Prior work on attacking VCS shows
that the hidden voice commands that are incomprehensible to people can control
the systems. Hidden voice commands, though hidden, are nonetheless audible. In
this work, we design a completely inaudible attack, DolphinAttack, that
modulates voice commands on ultrasonic carriers (e.g., f > 20 kHz) to achieve
inaudibility. By leveraging the nonlinearity of the microphone circuits, the
modulated low frequency audio commands can be successfully demodulated,
recovered, and more importantly interpreted by the speech recognition systems.
We validate DolphinAttack on popular speech recognition systems, including
Siri, Google Now, Samsung S Voice, Huawei HiVoice, Cortana and Alexa. By
injecting a sequence of inaudible voice commands, we show a few
proof-of-concept attacks, which include activating Siri to initiate a FaceTime
call on iPhone, activating Google Now to switch the phone to the airplane mode,
and even manipulating the navigation system in an Audi automobile. We propose
hardware and software defense solutions. We validate that it is feasible to
detect DolphinAttack by classifying the audios using supported vector machine
(SVM), and suggest to re-design voice controllable systems to be resilient to
inaudible voice command attacks.Comment: 15 pages, 17 figure
Discovery of Highly Obscured Galaxies in the Zone of Avoidance
We report the discovery of twenty-five previously unknown galaxies in the
Zone of Avoidance. Our systematic search for extended extra-galactic sources in
the GLIMPSE and MIPSGAL mid-infrared surveys of the Galactic plane has revealed
two overdensities of these sources, located around l ~ 47 and 55 degrees and
|b| less than 1 degree in the Sagitta-Aquila region. These overdensities are
consistent with the local large-scale structure found at similar Galactic
longitude and extending from |b| ~ 4 to 40 degrees. We show that the infrared
spectral energy distribution of these sources is indeed consistent with those
of normal galaxies. Photometric estimates of their redshift indicate that the
majority of these galaxies are found in the redshift range z = 0.01 - 0.05,
with one source located at z = 0.07. Comparison with known sources in the local
Universe reveals that these galaxies are located at similar overdensities in
redshift space. These new galaxies are the first evidence of a bridge linking
the large-scale structure between both sides of the Galactic plane at very low
Galactic latitude and clearly demonstrate the feasibility of detecting galaxies
in the Zone of Avoidance using mid-to-far infrared surveys.Comment: Accepted for publication in the Astronomical Journal, 28 pages, 5
tables, 11 figure
The M33 Globular Cluster System with PAndAS Data: The Last Outer Halo Cluster?
We use CFHT/MegaCam data to search for outer halo star clusters in M33 as
part of the Pan-Andromeda Archaeological Survey (PAndAS). This work extends
previous studies out to a projected radius of 50 kpc and covers over 40 square
degrees. We find only one new unambiguous star cluster in addition to the five
previously known in the M33 outer halo (10 kpc <= r <= 50 kpc). Although we
identify 2440 cluster candidates of various degrees of confidence from our
objective image search procedure, almost all of these are likely background
contaminants, mostly faint unresolved galaxies. We measure the luminosity,
color and structural parameters of the new cluster in addition to the five
previously-known outer halo clusters. At a projected radius of 22 kpc, the new
cluster is slightly smaller, fainter and redder than all but one of the other
outer halo clusters, and has g' ~ 19.9, (g'-i') ~ 0.6, concentration parameter
c ~ 1.0, a core radius r_c ~ 3.5 pc, and a half-light radius r_h ~ 5.5 pc. For
M33 to have so few outer halo clusters compared to M31 suggests either tidal
stripping of M33's outer halo clusters by M31, or a very different, much calmer
accretion history of M33.Comment: 37 pages, 9 figures. Accepted by the Astrophysical Journa
Experimental and Numerical aspects of B416 Cu-Be alloy friction stir process
The Friction Stir Processing is an innovative surface engineering method, considered as a green processing technique. A good physical understanding of the process can be reached by the combined efforts of experimental examination and numerical modelling. In this study numerical and experimental investigations of Friction Stir Process (FSP) have been carried out on samples of B194 ASTM copper-beryllium alloy. The behavior of this alloy under FSP was studied using an experiment design at three levels of transversal speed (maximum speed 80 mm/min), three different normal forces (maximum force 1250 N) and two levels of rotational speed: 1000 and 2000 rpm. The treated layers have been characterized in terms of hardness and microstructure. The results obtained have shown that FSP in the tested range of parameters leads to the formation of a stirred layer with fine grains and high hardness (approximately 260% higher that the initial value of the base material). The friction between the tool and the work piece generates heat around the tool and produces microstructure modification by homogenization and refinement. These factors play a crucial role in heat generation during the process. The heat generating mechanism is influenced by the process parameters (normal load, rotational speed, transverse speed and geometric data). Thus the present study has been carried out in order to investigate the coupled effects of process parameters and the tool geometry on the thermal behavior of B194 ASTM copper-beryllium alloy under friction stir process. Numerical analyses in terms of heat generation and temperature distribution were carried out and a three-dimensional heat transfer model for friction stir process is proposed in this paper
On the kinematics of the Local cosmic void
We collected the existing data on the distances and radial velocities of
galaxies around the Local Void in the Aquila/Hercules to examine the peculiar
velocity field induced by its underdensity. A sample of 1056 galaxies with
distances measured from the Tip of the Red Giant Branch, the Cepheid
luminosity, the SNIa luminosity, the surface brightness fluctuation method, and
the Tully-Fisher relation has been used for this purpose. The amplitude of
outflow is found to be ~300 km/s. The galaxies located within the void produce
the mean intra-void number density about 1/5 of the mean external number
density of galaxies. The void's population has a lower luminosity and a later
morphological type with the medians: M_B = -15.7^m and T = 8 (Sdm),
respectively.Comment: Version 1. 14 pages, 8 figures, 2 tables. Accepted to Astrophysics,
Volume 54, Issue
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