170 research outputs found
A dynamic model to assess the carrying capacity of a defined system
A system dynamics method to assess carrying capacity of a defined natural environment is presented. The proposed method seeks to relate per capita resource usage to ranges of population and per capita consumption beyond which the system is not viable relative to population dependent resource constraints. It provides a platform to investigate system behavior through system dynamics simulations where populations change, natural resources decay due to stressor impacts, and feedback occurs via implementation of policy. Application of the model to a case study of Total Maximum Daily Load (TMDL) of phosphorous in Bear Lake, a Lake Michigan estuary (USA), shows the major total phosphorous (P) loading contribution is anthropogenic land use development. Three scenarios are quantitatively explored by assuming changes in land use and/or loading rates. Simulation results show tradeoffs between reduction of total P and land use; economic development can be flexibly evaluated against targets of loading reduction trajectories
Uno studio sulla massima deflessione degli ultra-high-energy cosmic rays da parte dei campi magnetici primordiali
Gli Ultra-High-Energy Cosmic Rays sono dei raggi cosmici-dotati di energia
estremamente elevata-che raggiungono la Terra con un bassissimo rateo e dei
quali abbiamo pochi dati a riguardo; le incertezze riguardano la loro composizione, la loro sorgente, i metodi di accelerazione e le caratteristiche dei campi
magnetici che li deviano durante il loro cammino. L’obiettivo di questo studio
è determinare quali modelli di campo magnetico possano descrivere correttamente la propagazione degli UHECRs, andando a fare un confronto con i dati
sperimentali a disposizione; infatti, quello che osserviamo è una distribuzione
isotropa nel cielo e, di conseguenza, i modelli teorici di propagazione, per poter
essere accettati, devono rispecchiare tale comportamento. Sono stati testati
nove modelli di campo magnetico tratti da simulazioni cosmologiche, andando
a considerare due diverse composizione per i CRs (simil-ferro e simil-protone)
e il risultato ha dato delle risposte positive solo per tre di essi. Tali modelli,
per cui troviamo accordo, sono caratterizzati da una scala di inomegeneità più
ampia rispetto a quella dei modelli scartati, infatti, analizzando il loro spettro
di potenza, il maggior contributo è dato da fluttuazioni di campo magnetico su
scale di 10 Mpc. Ciò naturalmente, viste anche le poche informazioni riguardo
ai campi magnetici intergalattici, ci porta a pensare che campi di questo tipo
siano favoriti. Inoltre, per tali modelli, gli esiti sono risultati particolarmente
in accordo con i dati sperimentali, considerando CRs con composizione simile
al ferro: ciò fa pensare che tale composizione possa essere quella effettiva
Runtime Monitoring On Hard Real-Time Operating Systems
This thesis will compare and evaluate different approaches in integrating runtime monitors into processes running on a hard real-time operating system. The host system is a single board computer (SBC) with a VxWorks 653 hard real-time operating system henceforth referred to as a flight control computer (FCC). The FCC is an integrated modular avionics (IMA) system representative of actual flight computers. VxWorks 653 is based on the ARINC 653 standard and provides time and space partitioning for IMA systems.M.S
Highlights from the Pierre Auger Observatory
The Pierre Auger Observatory is the world's largest cosmic ray observatory.
Our current exposure reaches nearly 40,000 km str and provides us with an
unprecedented quality data set. The performance and stability of the detectors
and their enhancements are described. Data analyses have led to a number of
major breakthroughs. Among these we discuss the energy spectrum and the
searches for large-scale anisotropies. We present analyses of our X
data and show how it can be interpreted in terms of mass composition. We also
describe some new analyses that extract mass sensitive parameters from the 100%
duty cycle SD data. A coherent interpretation of all these recent results opens
new directions. The consequences regarding the cosmic ray composition and the
properties of UHECR sources are briefly discussed.Comment: 9 pages, 12 figures, talk given at the 33rd International Cosmic Ray
Conference, Rio de Janeiro 201
Calibration of the Logarithmic-Periodic Dipole Antenna (LPDA) Radio Stations at the Pierre Auger Observatory using an Octocopter
An in-situ calibration of a logarithmic periodic dipole antenna with a
frequency coverage of 30 MHz to 80 MHz is performed. Such antennas are part of
a radio station system used for detection of cosmic ray induced air showers at
the Engineering Radio Array of the Pierre Auger Observatory, the so-called
Auger Engineering Radio Array (AERA). The directional and frequency
characteristics of the broadband antenna are investigated using a remotely
piloted aircraft (RPA) carrying a small transmitting antenna. The antenna
sensitivity is described by the vector effective length relating the measured
voltage with the electric-field components perpendicular to the incoming signal
direction. The horizontal and meridional components are determined with an
overall uncertainty of 7.4^{+0.9}_{-0.3} % and 10.3^{+2.8}_{-1.7} %
respectively. The measurement is used to correct a simulated response of the
frequency and directional response of the antenna. In addition, the influence
of the ground conductivity and permittivity on the antenna response is
simulated. Both have a negligible influence given the ground conditions
measured at the detector site. The overall uncertainties of the vector
effective length components result in an uncertainty of 8.8^{+2.1}_{-1.3} % in
the square root of the energy fluence for incoming signal directions with
zenith angles smaller than 60{\deg}.Comment: Published version. Updated online abstract only. Manuscript is
unchanged with respect to v2. 39 pages, 15 figures, 2 table
Operations of and Future Plans for the Pierre Auger Observatory
Technical reports on operations and features of the Pierre Auger Observatory,
including ongoing and planned enhancements and the status of the future
northern hemisphere portion of the Observatory. Contributions to the 31st
International Cosmic Ray Conference, Lodz, Poland, July 2009.Comment: Contributions to the 31st ICRC, Lodz, Poland, July 200
Multi-resolution anisotropy studies of ultrahigh-energy cosmic rays detected at the Pierre Auger Observatory
We report a multi-resolution search for anisotropies in the arrival
directions of cosmic rays detected at the Pierre Auger Observatory with local
zenith angles up to and energies in excess of 4 EeV ( eV). This search is conducted by measuring the angular power spectrum
and performing a needlet wavelet analysis in two independent energy ranges.
Both analyses are complementary since the angular power spectrum achieves a
better performance in identifying large-scale patterns while the needlet
wavelet analysis, considering the parameters used in this work, presents a
higher efficiency in detecting smaller-scale anisotropies, potentially
providing directional information on any observed anisotropies. No deviation
from isotropy is observed on any angular scale in the energy range between 4
and 8 EeV. Above 8 EeV, an indication for a dipole moment is captured; while no
other deviation from isotropy is observed for moments beyond the dipole one.
The corresponding -values obtained after accounting for searches blindly
performed at several angular scales, are in the case of
the angular power spectrum, and in the case of the needlet
analysis. While these results are consistent with previous reports making use
of the same data set, they provide extensions of the previous works through the
thorough scans of the angular scales.Comment: Published version. Added journal reference and DOI. Added Report
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