4,280 research outputs found
Wind measurement system
A system for remotely measuring vertical and horizontal winds present in discrete volumes of air at selected locations above the ground is described. A laser beam is optically focused in range by a telescope, and the output beam is conically scanned at an angle about a vertical axis. The backscatter, or reflected light, from the ambient particulates in a volume of air, the focal volume, is detected for shifts in wavelength, and from these, horizontal and vertical wind components are computed
Optimal symmetric flight studies
Several topics in optimal symmetric flight of airbreathing vehicles are examined. In one study, an approximation scheme designed for onboard real-time energy management of climb-dash is developed and calculations for a high-performance aircraft presented. In another, a vehicle model intermediate in complexity between energy and point-mass models is explored and some quirks in optimal flight characteristics peculiar to the model uncovered. In yet another study, energy-modelling procedures are re-examined with a view to stretching the range of validity of zeroth-order approximation by special choice of state variables. In a final study, time-fuel tradeoffs in cruise-dash are examined for the consequences of nonconvexities appearing in the classical steady cruise-dash model. Two appendices provide retrospective looks at two early publications on energy modelling and related optimal control theory
Suzbijanje geografskog širenja zaraze: kuga u Italiji od 1347.-1851.
After the establishment of the first quarantine station in the Republic of Ragusa (modern-day Dubrovnik) in 1377, the states and principalities of Italy developed a sophisticated system of defensive quarantine in an attempt to protect themselves from the ravages of plague. Using largely unknown and unseen historical maps, this paper reconstructs the extent and operation of the system used. It is shown that a cordon sanitaire existed around the coast of Italy for several centuries, consisting of three elements: (i) an outer defensive ring of armed sailing boats in the Mediterranean and the Adriatic, (ii) a middle coastal ring of forts and observation towers, and (iii) an inner defensive ring of land-based cavalry. The principles established, although not especially successful at the time against a disease of (then) unknown aetiology, are still used today in attempts to control the spread of infections of animal and human populations.Nakon uspostave prvoga lazareta u Dubrovačkoj Republici 1377., talijanske državice i kneževine razradile su sustav karantena kako bi se zaštitile od razarajućega djelovanja kuge. Oslanjajući se mahom na dosad nepoznate povijesne karte, u ovome se članku rekonstruira kako je i u kojem razmjeru djelovao sustav zaštite. Duž talijanske obale stoljećima je postojao sanitarni kordon, a sastojao se od tri dijela: (i) vanjski pojas sastavljen od naoružanih jedrenjaka na Sredozemnom i Jadranskome moru, (ii) srednji obrambeni pojas sastavljen od utvrda i promatračnica te (iii) unutarnji obrambeni pojas na kopnu sastavljen od konjice. Premda ovaj sustav svojevremeno i nije bio pretjerano uspješan u zaštiti od bolesti (tada) nepoznate etiologije, njegova se načela još uvijek rabe za sprječavanje širenja bolesti među ljudima i životinjama
RoboCup 2D Soccer Simulation League: Evaluation Challenges
We summarise the results of RoboCup 2D Soccer Simulation League in 2016
(Leipzig), including the main competition and the evaluation round. The
evaluation round held in Leipzig confirmed the strength of RoboCup-2015
champion (WrightEagle, i.e. WE2015) in the League, with only eventual finalists
of 2016 competition capable of defeating WE2015. An extended, post-Leipzig,
round-robin tournament which included the top 8 teams of 2016, as well as
WE2015, with over 1000 games played for each pair, placed WE2015 third behind
the champion team (Gliders2016) and the runner-up (HELIOS2016). This
establishes WE2015 as a stable benchmark for the 2D Simulation League. We then
contrast two ranking methods and suggest two options for future evaluation
challenges. The first one, "The Champions Simulation League", is proposed to
include 6 previous champions, directly competing against each other in a
round-robin tournament, with the view to systematically trace the advancements
in the League. The second proposal, "The Global Challenge", is aimed to
increase the realism of the environmental conditions during the simulated
games, by simulating specific features of different participating countries.Comment: 12 pages, RoboCup-2017, Nagoya, Japan, July 201
Novelty Search in Competitive Coevolution
One of the main motivations for the use of competitive coevolution systems is
their ability to capitalise on arms races between competing species to evolve
increasingly sophisticated solutions. Such arms races can, however, be hard to
sustain, and it has been shown that the competing species often converge
prematurely to certain classes of behaviours. In this paper, we investigate if
and how novelty search, an evolutionary technique driven by behavioural
novelty, can overcome convergence in coevolution. We propose three methods for
applying novelty search to coevolutionary systems with two species: (i) score
both populations according to behavioural novelty; (ii) score one population
according to novelty, and the other according to fitness; and (iii) score both
populations with a combination of novelty and fitness. We evaluate the methods
in a predator-prey pursuit task. Our results show that novelty-based approaches
can evolve a significantly more diverse set of solutions, when compared to
traditional fitness-based coevolution.Comment: To appear in 13th International Conference on Parallel Problem
Solving from Nature (PPSN 2014
Design of Rail Instrumentation for Wind Tunnel Sonic Boom Measurements and Computational-Experimental Comparisons
An innovative pressure rail concept for wind tunnel sonic boom testing of modern aircraft configurations with very low overpressures was designed with an adjoint-based solution-adapted Cartesian grid method. The computational method requires accurate free-air calculations of a test article as well as solutions modeling the influence of rail and tunnel walls. Specialized grids for accurate Euler and Navier-Stokes sonic boom computations were used on several test articles including complete aircraft models with flow-through nacelles. The computed pressure signatures are compared with recent results from the NASA 9- x 7-foot Supersonic Wind Tunnel using the advanced rail design
Q-Strategy: A Bidding Strategy for Market-Based Allocation of Grid Services
The application of autonomous agents by the provisioning and usage of computational services is an attractive research field. Various methods and technologies in the area of artificial intelligence, statistics and economics are playing together to achieve i) autonomic service provisioning and usage of Grid services, to invent ii) competitive bidding strategies for widely used market mechanisms and to iii) incentivize consumers and providers to use such market-based systems.
The contributions of the paper are threefold. First, we present a bidding agent framework for implementing artificial bidding agents, supporting consumers and providers in technical and economic preference elicitation as well as automated bid generation by the requesting and provisioning of Grid services. Secondly, we introduce a novel consumer-side bidding strategy, which enables a goal-oriented and strategic behavior by the generation and submission of consumer service requests and selection of provider offers. Thirdly, we evaluate and compare the Q-strategy, implemented within the presented framework, against the Truth-Telling bidding strategy in three mechanisms – a centralized CDA, a decentralized on-line machine scheduling and a FIFO-scheduling mechanisms
Small world effect in an epidemiological model
A model for the spread of an infection is analyzed for different population
structures. The interactions within the population are described by small world
networks, ranging from ordered lattices to random graphs. For the more ordered
systems, there is a fluctuating endemic state of low infection. At a finite
value of the disorder of the network, we find a transition to self-sustained
oscillations in the size of the infected subpopulation
On the information-theoretic formulation of network participation
The participation coefficient is a widely used metric of the diversity of a
node's connections with respect to a modular partition of a network. An
information-theoretic formulation of this concept of connection diversity,
referred to here as participation entropy, has been introduced as the Shannon
entropy of the distribution of module labels across a node's connected
neighbors. While diversity metrics have been studied theoretically in other
literatures, including to index species diversity in ecology, many of these
results have not previously been applied to networks. Here we show that the
participation coefficient is a first-order approximation to participation
entropy and use the desirable additive properties of entropy to develop new
metrics of connection diversity with respect to multiple labelings of nodes in
a network, as joint and conditional participation entropies. The
information-theoretic formalism developed here allows new and more subtle types
of nodal connection patterns in complex networks to be studied
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