18 research outputs found
Quantification and Modeling of Broken Links Prevalence in Hyper Traffic Websites Homepages
Broken links in websites external resources pose a serious threat to
cybersecurity and the credibility of websites. They can be hijacked to
eavesdrop user traffic or to inject malicious software. In this paper, we
present the first result of an ongoing research. We focus on the prevalence of
broken links in external resources on home pages of the most visited websites
in the world. The analysis was conducted on the top 88 000 homepages extracted
from the Majestic Million rankings. 35,2% of them have at least one broken
link. We also identify the common causes of these broken links and highlight
improper implementation of testing phases to prevent such errors. We provide a
formal model for the distribution of external links. At the next research step,
we are exploring the potential impact on privacy of broken links by analyzing
inherited traffic of purchasable expired domains.Comment: 4 pages, 3 tables, 1 figur
Reagentless and silicate interference free electrochemical phosphate determination in seawater
An electrochemical method for phosphate determination in seawater was based on the oxidation of molybdenum in order to form molybdates and protons and subsequently, to create the phosphomolybdic complex electrochemically detectable by means of amperometry at a rotating gold disk electrode [J. Jonca et al., Talanta 87 (2011) 161]. To avoid silicate interferences, the method required an appropriate ratio of protons over molybdates equal to 70. Since the ratio of protons over molybdates created during molybdenum oxidation is only 8, the previous method still needed addition of sulfuric acid and thus was not free from addition of liquid reagents. In the present work, this aspect is solved by modification of the electrochemical cell construction. The method is now totally free from addition of any liquid reagents and gives a possibility to determine phosphate by amperometry in the concentrations range found in the open ocean with a detection limit of 0.11 µM. Having in mind the energy savings for future in situ sensor development, amperometry at rotating gold disk electrode was replaced by differential pulse voltammetry at static one. Phosphate can then be determined with a detection limit of 0.19 µM. Both methods are characterized by good reproducibility with an average measurements precision of 5.7% (amperometry) and 3.8% (differential pulse voltammetry). Results also show a good accuracy with an average deviation from theoretical values of phosphate concentration of 3.1% for amperometry and 3.7% for differential pulse voltammetry
AstroPix: novel monolithic active pixel silicon sensors for future gamma-ray telescopes
Space-based gamma-ray telescopes such as the Fermi Large Area Telescope have used single sided silicon strip detectors to track secondary charged particles produced by primary gamma-rays with high resolution. At the lower energies targeted by keV-MeV telescopes, two dimensional position information within a single detector is required for event reconstruction - especially in the Compton regime. This work describes the development of monolithic CMOS active pixel silicon sensors - AstroPix - as a novel technology for use in future gamma-ray telescopes. Based upon sensors (ATLASPix) designed for use in the ATLAS detector at the Large Hadron Collider, AstroPix has the potential to maintain high performance while reducing noise with low power consumption. This is achieved with the dual detection and readout capabilities in each CMOS pixel. The status of AstroPix development and testing, as well as outlook for future testing and application, will be presented
AstroPix: CMOS pixels in space
Space-based gamma-ray telescopes such as the Fermi Large Area Telescope have used single sided silicon strip detectors to measure the position of charged particles produced by incident gamma rays with high resolution. At energies in the Compton regime and below, two dimensional position information within a single detector is required. Double sided silicon strip detectors are one option; however, this technology is difficult to fabricate and large arrays are susceptible to noise. This work outlines the development and implementation of monolithic CMOS active pixel silicon sensors, AstroPix, for use in future gamma-ray telescopes. Based upon detectors designed using the HVCMOS process at the Karlsruhe Institute of Technology, AstroPix has the potential to maintain the high energy and angular resolution required of a medium-energy gamma- ray telescope while reducing noise with the dual detection-and-readout capabilities of a CMOS chip. The status of AstroPix development and testing as well as outlook for application in future telescopes is presented
The Raman Laser Spectrometer for the ExoMars Rover Mission to Mars
The Raman Laser Spectrometer (RLS) on board the ESA/Roscosmos ExoMars 2020 mission will provide
precise identification of the mineral phases and the possibility to detect organics on the Red Planet. The RLS
will work on the powdered samples prepared inside the Pasteur analytical suite and collected on the surface and
subsurface by a drill system. Raman spectroscopy is a well-known analytical technique based on the inelastic
scattering by matter of incident monochromatic light (the Raman effect) that has many applications in laboratory
and industry, yet to be used in space applications. Raman spectrometers will be included in two Mars
rovers scheduled to be launched in 2020. The Raman instrument for ExoMars 2020 consists of three main units:
(1) a transmission spectrograph coupled to a CCD detector; (2) an electronics box, including the excitation laser
that controls the instrument functions; and (3) an optical head with an autofocus mechanism illuminating and
collecting the scattered light from the spot under investigation. The optical head is connected to the excitation
laser and the spectrometer by optical fibers. The instrument also has two targets positioned inside the rover
analytical laboratory for onboard Raman spectral calibration. The aim of this article was to present a detailed
description of the RLS instrument, including its operation on Mars. To verify RLS operation before launch and
to prepare science scenarios for the mission, a simulator of the sample analysis chain has been developed by the
team. The results obtained are also discussed. Finally, the potential of the Raman instrument for use in field
conditions is addressed. By using a ruggedized prototype, also developed by our team, a wide range of
terrestrial analog sites across the world have been studied. These investigations allowed preparing a large
collection of real, in situ spectra of samples from different geological processes and periods of Earth evolution.
On this basis, we are working to develop models for interpreting analog processes on Mars during the mission.
Key Words: Raman spectroscopy—ExoMars mission—Instruments and techniques—Planetary sciences—Mars
mineralogy and geochemistry—Search for life on Mars. Astrobiology 17, 627–65
The All-sky Medium Energy Gamma-ray Observatory eXplorer (AMEGO-X) Mission Concept
The All-sky Medium Energy Gamma-ray Observatory eXplorer (AMEGO-X) is
designed to identify and characterize gamma rays from extreme explosions and
accelerators. The main science themes include: supermassive black holes and
their connections to neutrinos and cosmic rays; binary neutron star mergers and
the relativistic jets they produce; cosmic ray particle acceleration sources
including Galactic supernovae; and continuous monitoring of other astrophysical
events and sources over the full sky in this important energy range. AMEGO-X
will probe the medium energy gamma-ray band using a single instrument with
sensitivity up to an order of magnitude greater than previous telescopes in the
energy range 100 keV to 1 GeV that can be only realized in space. During its
three-year baseline mission, AMEGO-X will observe nearly the entire sky every
two orbits, building up a sensitive all-sky map of gamma-ray sources and
emission. AMEGO-X was submitted in the recent 2021 NASA MIDEX Announcement of
Opportunity.Comment: 23 pages, 16 figures, Published Journal of Astronomical Telescopes,
Instruments, and System
The SuperCam Instrument Suite on the Mars 2020 Rover: Science Objectives and Mast-Unit Description
On the NASA 2020 rover mission to Jezero crater, the remote determination of the texture, mineralogy and chemistry of rocks is essential to quickly and thoroughly characterize an area and to optimize the selection of samples for return to Earth. As part of the Perseverance payload, SuperCam is a suite of five techniques that provide critical and complementary observations via Laser-Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman and Luminescence (TRR/L), visible and near-infrared spectroscopy (VISIR), high-resolution color imaging (RMI), and acoustic recording (MIC). SuperCam operates at remote distances, primarily 2-7 m, while providing data at sub-mm to mm scales. We report on SuperCam's science objectives in the context of the Mars 2020 mission goals and ways the different techniques can address these questions. The instrument is made up of three separate subsystems: the Mast Unit is designed and built in France; the Body Unit is provided by the United States; the calibration target holder is contributed by Spain, and the targets themselves by the entire science team. This publication focuses on the design, development, and tests of the Mast Unit; companion papers describe the other units. The goal of this work is to provide an understanding of the technical choices made, the constraints that were imposed, and ultimately the validated performance of the flight model as it leaves Earth, and it will serve as the foundation for Mars operations and future processing of the data.In France was provided by the Centre National d'Etudes Spatiales (CNES). Human resources were provided in part by the Centre National de la Recherche Scientifique (CNRS) and universities. Funding was provided in the US by NASA's Mars Exploration Program. Some funding of data analyses at Los Alamos National Laboratory (LANL) was provided by laboratory-directed research and development funds
Sea level monitoring and sea state estimate using a single geodetic receiver
International audienc
AstroPix: novel monolithic active pixel silicon sensors for future gamma-ray telescopes
Space-based γ-ray telescopes such as the Fermi Large Area Telescope have used single sided silicon strip detectors to track secondary charged particles produced by primary γ-rays with high resolution. At the lower energies targeted by keV-MeV telescopes, two dimensional position information within a single detector is required for event reconstruction—especially in the Compton regime. This work describes the development of monolithic CMOS active pixel silicon sensors—AstroPix—as a novel technology for use in future γ-ray telescopes. Based upon sensors (ATLASPix) designed for use in the ATLAS detector at the Large Hadron Collider, AstroPix has the potential to maintain high performance while reducing noise with low power consumption. This is achieved with the dual detection and readout capabilities in each CMOS pixel. The status of AstroPix development and testing, as well as outlook for future testing and application, will be presented