577 resultados para Gyro compass
Resumo:
Without an absolute position sensor (e.g., GPS), an accurate heading estimate is necessary for proper localization of an autonomous unmanned vehicle or robot. This paper introduces direction maps (DMs), which represent the directions of only dominant surfaces of the vehicle’s environment and can be created with negligible effort. Given an environment with reoccurring surface directions (e.g., walls, buildings, parked cars), lines extracted from laser scans can be matched with a DM to provide an extremely lightweight heading estimate that is shown, through experimentation, to drastically reduce the growth of heading errors. The algorithm was tested using a Husky A200 mobile robot in a warehouse environment over traverses hundreds of metres in length. When a simple a priori DM was provided, the resulting heading estimation showed virtually no error growth.
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Fairies and fairy tales continue to intrigue both academic and popular audiences. This article, while exploring the diverse approaches of recent scholars in this field, also raises disciplinary questions. Should the study of folklore and of the literary fairy tale be seen as separate research areas, one the preserve of the cultural historian and folklorist, the other the remit of the literary scholar? Can we even make a clear distinction in the nineteenth century between authored, literary fairy tales and orally collected supernatural folktales? If it is reductive to assume that the fairy tale can always be classified (and potentially dismissed) as children's literature, how might recent trends in Victorian studies suggest new ways of seeing and teaching the genre? Discussing the fairy tale in the context of debates over orality and authenticity, literature and science, all of these questions will be examined below.
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Recent evidence suggests that bats can detect the geomagnetic field, but the way in which this is used by them for navigation to a home roost remains unresolved. The geomagnetic field may be used by animals both to indicate direction and to locate position. In birds, directional information appears to be derived from an interaction of the magnetic field with either the sun or the stars, with some evidence suggesting that sunset/sunrise provides the primary directional reference by which a magnetic compass is calibrated daily. We demonstrate that homing greater mouse-eared bats (Myotis myotis) calibrate a magnetic compass with sunset cues by testing their homing response after exposure to an altered magnetic field at and after sunset. Magnetic manipulation at sunset resulted in a counterclockwise shift in orientation compared with controls, consistent with sunset calibration of the magnetic field, whereas magnetic manipulation after sunset resulted in no change in orientation. Unlike in birds, however, the pattern of polarization was not necessary for the calibration. For animals that occupy ecological niches where the sunset is rarely observed, this is a surprising finding. Yet it may indicate the primacy of the sun as an absolute geographical reference not only for birds but also within other vertebrate taxa.
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Several animals and microbes have been shown to be sensitive to magnetic fields, though the exact mechanisms of this ability remain unclear in many animals. Chitons are marine molluscs which have high levels of biomineralised magnetite coating their radulae. This discovery led to persistent anecdotal suggestions that they too may be able to navigationally respond to magnetic fields. Several researchers have attempted to test this, but to date there have been no large-scale controlled empirical trials. In the current study, four chiton species (Katharina tunicata, Mopalia kennerleyi, Mopalia muscosa and Leptochiton rugatus, n=24 in each) were subjected to natural and artificially rotated magnetic fields while their movement through an arena was recorded over four hours. Field orientation did not influence the position of the chitons at the end of trials, possibly as a result of the primacy of other sensory cues (i.e. thigmotaxis). Under non-rotated magnetic field conditions, the orientation of subjects when they first reached the edge of an arena was clustered around 309-345 degrees (north-north-west) in all four species. However, orientations were random under the rotated magnetic field, which may indicate a disruptive effect of field rotation. This pattern suggests that chitons can detect and respond to magnetism.
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In a recent study, Greif et al. (2014) demonstrated a functional role of polarized light for a bat species confronted with a homing task. These non-migratory bats appeared to calibrate their magnetic compass by using polarized skylight at dusk, yet it is unknown if migratory bats also use these cues for calibration. During autumn migration, we equipped Nathusius' bats, Pipistrellus nathusii, with radio transmitters and tested if experimental animals exposed to a 90° rotated band of polarized light during dusk, would head in a different direction compared with control animals. After release, bats of both groups continued their journey in the same direction. This observation argues against the use of a polarization-calibrated magnetic compass by this migratory bat and questions that the ability of using polarized light for navigation is a consistent feature in bats. This finding matches with observations in some passerine birds that used polarized light for calibration of their magnetic compass before but not during migration.
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Brass Surveying Compass with a 6 1/2 inch diameter silvered brass dial signed E. and G.W. Blunt of New York. There is a fleur-de-lis at the north point and the outer needle ring is engraved 0-90 in four quadrants. There is an engraved central pattern, blue steel hand and brass lifter, shaped limbs and a brass dial cover. This belonged to Samuel DeVeaux Woodruff who was a Civil Engineer. It also belonged to R.D.W. Band who was also a Civil Engineer. Also, One 13 cm. brass spindle taper for the surveying compass, n.d
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A method for in situ detection of atmospheric turbulence has been developed using an inexpensive sensor carried within a conventional meteorological radiosonde. The sensor-a Hall effect magnetometer-was used to monitor the terrestrial magnetic field. Rapid time scale (10 s or less) fluctuations in the magnetic field measurement were related to the motion of the radiosonde, which was strongly influenced by atmospheric turbulence. Comparison with cloud radar measurements showed turbulence in regions where rapid time-scale magnetic fluctuations occurred. Reliable measurements were obtained between the surface and the stratosphere.
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With transnational corporations (TNCs) around the world today numbering over 60,000 and more than 800,000 affiliates working abroad, it is easy to understand how modern day international business could have transformed into a major global player serving at the axis of politics, social and environmental responsibility. Additionally, with accountability to a large variety of both public and private stakeholders, all exerting significant power and influence, today’s global corporate structure is reinventing modern international relations, and in some cases, dominating it. (Muldoon 2005) This transformative nature of globalization today can also serve as a source of friction among this growing chorus of players and is bringing irreversible change to these relationships and how they impact and influence business around the world. (Muldoon 2005) From the largest to the smallest international corporation seeking to expand into new international markets, the challenges that come with corporate ambition can mean the difference between success and failure and they find a home at the intersection of international relations, diplomacy and economics. To successfully navigate these challenges, especially in emerging economies, a company must now factor in more than just the “bottom line” and address complex issues that include human rights differences, environmental regulations, labor rights and values of each country. (Henisz, 2014) Combined with modern-day mobility achieved through technology and the Internet, corporations today have a great capacity to reach targeted audiences and establish a presence, but it is this same technology that also allows for immediate response to any corporate action. This constant, 24-hour news cycle, where everyone is made to be a real-time reporter through social media, has created a situation that demonstrably necessitates the ability to not only 3 respond immediately, but also to have real-time understanding of the challenges faced by a corporation as it looks toward global expansion. International Business Diplomacy, or simply Business Diplomacy as it will be referred to in this paper, combines all of these nuanced factors into a relatively new discipline that offers companies looking to expand into new markets, guidelines and directives so that they can more strategically map corporate direction, limit risk and achieve their objectives. This paper will examine the history of diplomacy and how the concept of statecraft became intertwined with the increasing globalization of business. Following a scholarly examination of how modern Business Diplomacy came into being, and the unique challenges that come with its application, particularly the liabilities needed to be overcome, this paper will apply the concept to the Brazilian aerospace manufacturer Embraer, tracking its strategic emergence from a small, regionally focused aircraft producer to global leader in the regional and executive jet market platforms. It will then examine Embraer’s entrance into the Chinese market, where the company suffered from several missteps and eventually had to refocus its business model from commercial to executive jets. Finally, as globalization continues to “emancipate international business from its institutional and social constraints,” (Muldoon 2005) this paper will address how the relatively new and emerging discipline of Business Diplomacy is continuing to mature and grow in stature and influence through the proposition of a new challenge or “liability” that corporations must also overcome as they expand into new markets. Through the analysis of Embraer in China, this paper will introduce the Liability of Governance to the lexicon of Business Diplomacy and propose specific steps that a company can undertake to avoid it.
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Ein wesentliches Ziel des COMPASS Experiments am CERN istdie direkte Messung der Gluonpolarisation in derinelastischen Streuung von polarisierten 160 GeV Myonen aneinem polarisierten Nukleon Target. In der inelastischenLepton-Nukleon-Streuung erlaubt der sog.Photon-Gluon-Fusions-Prozess (PGF) die Untersuchung derGluonverteilung.Im Rahmen der vorliegenden Arbeit wurde ein Triggersystementwickelt und aufgebaut, das gezielt PGF-Reaktionenselektiert. Das System basiert auf demkoinzidenten Nachweis der gestreuten Myonen zusammen mit denproduzierten Hadronen und generiert innerhalb 600 ns einhochselektives Triggersignal. Der Wirkungsquerschnitt derPGF wird von Ereignissen mit quasi-reellen Photonendominiert, d.h. der Myonstreuwinkel ist kein geeignetesKriterium um die gestreuten Myonen von den Strahlmyonen zutrennen, deshalb muss der Energieverlust des Myons verwendetwerden. Der sog. Energieverlusttrigger besteht aus Paarenvon Plastikszintillatorhodoskopen mit exzellenter Zeitaufloesung, die zusammen mit einer selbstentwickeltenschnellen Koinzidenzelektronik eine Koinzidenzzeit vonweniger als 3ns möglich macht. Fuer den gleichzeitigenNachweis der Hadronen wurden die beiden Hadronkalorimeterdes COMPASS--Spektrometers mit einer eigens entwickeltenElektronik versehen.
Resumo:
One of the main goals of the COMPASS experiment at CERN is the
determination of the gluon polarisation in the nucleon. It is determined from spin asymmetries in the scattering of
160 GeV/c polarised muons on a polarised LiD target.
The gluon polarisation is accessed by the selection of photon-gluon fusion (PGF) events. The PGF-process can be tagged through hadrons with high transverse momenta or through charmed hadrons in the final state. The advantage of the open charm channel is that, in leading order, the PGF-process is the only process for charm production, thus no physical background contributes to the selected data sample.
This thesis presents a measurement of the gluon polarisation from the COMPASS data taken in the years 2002-2004. In the analysis, charm production is tagged through a
reconstructed D0-meson decaying in $D^{0}-> K^{-}pi^{+}$ (and charge conjugates). The reconstruction is done on a combinatorial basis. The background of wrong track pairs is reduced using kinematic cuts to the reconstructed D0-candidate and the information on particle identification from the Ring Imaging Cerenkov counter. In addition, the event sample is separated into D0-candidates, where a soft pion from the decay of the D*-meson to a D0-meson, is found, and the D0-candidates without this tag. Due to the small mass difference between D*-meson and D0-meson the signal purity of the D*-tagged sample is about 7 times higher than in the untagged sample.
The gluon polarisation is measured from the event asymmetries for the for the different spin configurations of the COMPASS target. To improve the statistical precision of the final results, the events in the final sample are weighted.
This method results in an average value of the gluon polarisation in the x-range covered by the data. For the COMPASS data from 2002-2004, the resulting value of the gluon polarisation is $
Resumo:
The systematic exploration of excited meson and baryon states was the central topic of the COMPASS physics program in the years 2008 and 2009 at the CERN facility. A hadron beam of 190 GeV/c particle momentum was impinging on a 40 cm long liquid hydrogen target to create excited states of beam particles by diffractive processes. The presented work is about the study of the process $K^- p rightarrow K^- pi^+ pi^- p_{recoil}$ where special emphasis is put on how kaons were distinguished from pions with the CEDAR detectors in the initial channel as well as with the RICH detector in the final states. At the end formed 270 000 events an invariant K pi pi mass distribution of overlapping resonances. In addition a detailed MC simulation study of 44 million decays in the range of 0.8 < m(K pi pi) [GeV/c^2] < 3.0 was performed and analysed for acceptance corrections.All information was combined into a mass independent partial wave analysis to observe resonances of individual particles. The main contribution was found in the JP = 0+, 1+, 2- and 2+ spin-parity states.