1,619 research outputs found
HLOC: Hints-Based Geolocation Leveraging Multiple Measurement Frameworks
Geographically locating an IP address is of interest for many purposes. There
are two major ways to obtain the location of an IP address: querying commercial
databases or conducting latency measurements. For structural Internet nodes,
such as routers, commercial databases are limited by low accuracy, while
current measurement-based approaches overwhelm users with setup overhead and
scalability issues. In this work we present our system HLOC, aiming to combine
the ease of database use with the accuracy of latency measurements. We evaluate
HLOC on a comprehensive router data set of 1.4M IPv4 and 183k IPv6 routers.
HLOC first extracts location hints from rDNS names, and then conducts
multi-tier latency measurements. Configuration complexity is minimized by using
publicly available large-scale measurement frameworks such as RIPE Atlas. Using
this measurement, we can confirm or disprove the location hints found in domain
names. We publicly release HLOC's ready-to-use source code, enabling
researchers to easily increase geolocation accuracy with minimum overhead.Comment: As published in TMA'17 conference:
http://tma.ifip.org/main-conference
Taxonomy of Oncaeidae (Copepoda, Poecilostomatoida) from the Red Sea. - IX. Epicalymma bulbosa sp. nov., first record of the genus from the Red Sea
The oncaeid genus Epicalymma comprises small copepod species usually living at meso- and bathypelagic depth layers in oceanic areas. The genus had previously been assumed to be absent from the Red Sea, due to the unusually high deep-sea temperatures and salinities in this area. In the present account a new species, Epicalymma bulbosa, is described from the Red Sea, which appears to be the only representative of the genus in the region. The new species is the smallest Epicalymma species so far recorded, with a total body length of ∼0.32 and ∼0.29 mm in the female and male, respectively. Apart from its small size, it differs from all known Epicalymma species by an extremely long exopodal seta on P5 in both sexes, and by a free exopod segment of P5 and a very long and basally swollen spinule on the syncoxa of the maxilliped in the female. In contrast to other Epicalymma species, which are distributed between 500 and >2500 m depth, the new species occurred much shallower (100–750 m) in the Red Sea, which may be interpretated as an avoidance mechanism of the unfavourable environmental conditions in the deep Red Sea. The taxonomic status of the new species within the genus Epicalymma is discussed and the few available ecological data on Epicalymma species in the world ocean are summarized
Atmospheric cycles of nitrogen oxides and ammonia
The atmospheric cycles of nitrogenous trace compounds for the Northern and Southern Hemispheres are discussed. Source strengths and destruction rates for the nitrogen oxides: NO, NO2 and HNO3 -(NOX) and ammonia (NH3) are given as a function of latitude over continents and oceans. The global amounts of NOX-N and NH3-N produced annually in the period 1950 to 1975 (34 + 5 x one trillion g NOx-N/yr and 29 + or - 6 x one trillion g NH3-N/yr) are much less than previously assumed. Globally, natural and anthropogenic emissions are of similar magnitude. The NOx emission from anthropogenic sources is 1.5 times that from natural processes in the Northern Hemisphere, whereas in the Southern Hemisphere, it is a factor of 3 or 4 less. More than 80% of atmospheric ammonia seems to be derived from excrements of domestic animals, mostly by bulk deposition: 24 + or - 9 x one trillion g NO3 -N/yr and 21 + or - 9 x one trillion g NH4+-N/yr. Another fraction may be removed by absorption on vegetation and soils
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GCM simulations of the martian water cycle
Results from the Viking Orbiter Mars Atmospheric
Water Detectors (MAWD) have long been the definitive
data set for observations of the Martian water cycle
(Farmer et al., 1977). The ongoing Mars Global Surveyor
Thermal Emission Spectrometer (TES) observations
are providing new insights into the current water
cycle, with detailed longitude-latitude dependence of
water vapour (Figure 1) and water cloud (Figure 2) with
time, as well as information on vertical distribution of
water vapour and ice cloud (Smith, 2001). The described
results are derived from an ongoing project to model the
currentwater cycle using the Oxford version of the European
Mars General Circulation Model (MGCM) (Forget
et al., 1999), which was developed in colaboration with
LMD, Paris
Does Familiarity With A Rape Victim Influence Rape Myth Acceptance?
Višerazinski izmjenjivači se koriste kod obnovljivih izvora energije, u električnim vozilima, u dizalima, u električnoj propulziji i u drugim električnim uređajima. Višerazinski izmjenjivači imaju manje gubitke na većim frekvencijama sklapanja. Imaju povoljniji harmonijski sastav izlaznih napona, te omogućavaju korištenje manjih EMI filtara. Smanjuju se pasivni elementi, i zahtjevi hlađenja. U višerazinskim izmjenjivačima koriste se sklopke manjeg naponskog razreda na višim naponima. U ovom radu izrađen je simulacijski model diodno pritegnutog trorazinskog izmjenjivača. Upotrebom simulacijskog modela analizirana su najvažnija svojstva ovog tipa izmjenjivača. Također je napravljena komparativna analiza karakteristika dvorazinskih i trorazinskih izmjenjivača pri spajanju fotonaponskog modula na pasivno izmjenično trošilo.Multilevel inverters are used in applications with renewable sources, electrical vehicles, elevators, electric propulsion and other electric devices. Multilevel inverters have lower losses on higher switching frequencies. They have better harmonic composition in output voltages enabling us to use smaller EMI filters. Passive elements and cooling requirements are decreased. In multilevel inverters switches with lower voltage class are used on higher voltages. In this paper a simulation model of diode-clamped three-level inverter is presented. With this simulation model are analysed the most important featured of this type of inverter. Also the comparative analysis of characteristics is made between two-level and three-level inverters connecting fotovoltaic module on passive AC load
Does environmental flow speed affect the local relative abundance of Vorticella convallaria?
Vorticella convallaria are microscopic sessile suspension feeders which live attached to substrates and are ubiquitous in aquatic environments. They depend on a self-generated current to feed and help maintain the health of aquatic ecosystems by consuming bacteria and detritus. As highly prevalent filter feeders, they serve as biological indicators of ecosystem health and are heavily involved in nutrient and carbon cycling. Furthermore, they are essential to wastewater treatment and benefit bioremediation efforts. However, the conditions in which they collectively thrive and feed most effectively are not well known. We exposed organisms to a circulating flume containing four distinct unidirectional flow regimes of different speeds. Initial results suggest that organisms are significantly more abundant in the slow speeds, in which they are less pushed over and may feed more effectively. Vorticella remained more abundant in the slowest flow speed over time, and became more abundant when the order of flow regimes was reversed (transforming a fast flow regime into one with a slower speed), indicative of selective preference
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