3,054 research outputs found
Expanded Parameters in the Self-Organized Critical Forest Fire Model
The forest fire model has frequently been used as a way to test the theory of Self-Organized Criticality, which is a model of complexity. The model analyzes commonalities in randomly generated forest fires using a computer simulation. In previous models, only the nearest neighbors to a tree on fire catch on fire, and it has been assumed that if further neighboring trees also catch on fire, then it will still exhibit self-organized criticality. Testing this assumption aids to the exploration of the applicability of self-organized criticality because the model is the most useful when it applies to a large range of systems, as closely related to nature as possible
Jet noise source distribution for coplanar nozzles: experiments and predictions
In this paper we study the mechanism of jet noise production in coaxial flows. We shall present
various experimental results for isothermal and heated coplanar jet flows of four area ratios (0.81,
2, 3, and 4), operating at different velocity ratios, ranging from 0.60 up to 1.26. A polar array
technique has been used to find the axial distribution of the jet sources. In order to better under-
stand the behavior of the experimental results, some computational fluid dynamics simulations are
performed, and a basic theoretical model based on Lighthillâs Acoustic Analogy is also developed.
It is shown that some significant changes occur to the flow structure and therefore the jet noise source distribution at velocity ratio of about 0.8, and also for the nozzles with area ratio of 2 to 4. It has also been shown that the most important high and low frequency sources for low velocity ratio flows are aggregated in a region about seven to ten secondary diameters downstream, while at higher velocity ratios sources are continuously spread from about one up to ten secondary diameters downstream. The effect of the primary flow temperature is also examined
Marketing Tourism In The Galapagos Islands: Ecotourism Or Greenwashing?
Tourism accounts for approximately 7.5% - 15% of the world’s total employment and is the world’s most important service industry. In heavily frequented tourist destinations such as the Galapagos Islands in Ecuador, the importance is even higher. International travel is projected to double by 2020 with over 1.5 billion people traveling throughout the world. Within the tourism industry, ecotourism is the fastest growing sector, growing from 10 to 30 percent a year. While exact definitions of ecotourism vary, ecotourism is defined by the International Tourism Society (TIES) as “responsible travel to natural areas that conserves the environment and improves the welfare of local people.” A subset of sustainable tourism, ecotourism has a natural area focus, which benefits the environment and communities visited, fosters environmental and cultural understanding, appreciation and awareness. Because there is no universally adopted certification program for ecotourism, tourism operators may market their operations as “ecotourism” while in reality they are “greenwashing.” Greenwashers are dishonest tourism operators who embrace ecotourism as a new selling angle. To greenwash is to promote ecotourism while effectively doing the opposite. The Galapagos Islands is a popular destination for ecotourism. Beginning in the late 1960’s, the Galapagos tourism industry started with about 1,000 tourists per year and has boomed to 148,000 tourists in 2006. This has caused several problems: growing human population, introduction of alien and invasive species, and unwanted by-products from tourism. As a result, in 2007, the Galapagos Islands were placed on UNESCO’s list of World Heritage Sites in Danger. Because of the unique biodiversity of the Galapagos Islands, and the increase in tourism and its negative consequences, the Galapagos Islands presents an excellent example for a case study in marketing of ecotourism. Using the criteria established by the Mohonk Agreement for responsible ecotourism, this paper examines the websites of ecotourism operators in the Galapagos Islands to determine the extent to which they are “ecotours” or “greenwashed tours.” The implications for conservation of the islands and responsible marketing are discussed
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Magma volume, volatile emissions, and stratospheric aerosols from the 1815 eruption of Tambora
We suggest that the Tambora 1815 eruption was smaller than previously thought, yielding 30â33 km3 of magma. Valuable insight into the eruption is gained by comparing it to the much smaller 1991 Pinatubo event, which had a similar eruption style and rate. By measuring pre- and post-eruption sulfur concentrations in 1815 ejecta, we estimate that Tambora released 53â58 Tg (5.3â5.8 Ă 1013 g) of SO2 within a period of about 24 hours on 10â11 April, 1815. This was sufficient to generate between 93 and 118 Tg of stratospheric sulfate aerosols. A value within this range, distributed globally, agrees well with estimates of aerosol mass from ice-core acidity and the radiative impact of the eruption. In contrast to other recent explosive arc eruptions, the Tambora ejecta retain a record of the sulfur mass released, with no âexcess sulfurâ
Early Modern Britainâs Relationship to Its Past: The Historiographical Fortunes of the Legends of Brute, Albina, and Scota
This volume considers the reception in the early modern period of four popular medieval myths of nationhoodâthe legends of Brutus, Albina, and Scotaâtracing their intertwined literary and historiographical afterlives. The book is particularly timely in its dialogue with current investigations into early modern historiography and the period\u27s relationship to its past, its engagement with pressing issues in identity and gender studies, and its analysis of British national origin stories at a time when modern Britain is considering its own future as a nation.https://scholarworks.wmich.edu/mip_rmemc/1005/thumbnail.jp
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Icelandic analogs to Martian flood lavas
We report on new field observations from Icelandic lava flows that have the same surface morphology as many Martian flood lava flows. The Martian flood lavas are characterized by a platy-ridged surface morphology whose formation is not well understood. The examples on Mars include some of the most pristine lava on the planet and flows >1500 km long. The surfaces of the flows are characterized by (1) ridges tens of meters tall and wide and hundreds of meters long, (2) plates hundreds of meters to kilometers across that are bounded by ridges, (3) smooth surfaces broken into polygons several meters across and bowed up slightly in the center, (4) parallel grooves 1â10 km long cut into the flow surface by flow past obstacles, and (5) inflated pahoehoe margins. The Icelandic examples we examined (the 1783â1784 Laki Flow Field, the BĂşrfells Lava Flow Field by Lake Myvatn, and a lava flow from Krafla Volcano) have all these surface characteristics. When examined in detail, we find that the surfaces of the Icelandic examples are composed primarily of disrupted pahoehoe. In some cases the breccia consists of simple slabs of pahoehoe lava; in other cases it is a thick layer dominated by contorted fragments of pahoehoe lobes. Our field observations lead us to conclude that these breccias are formed by the disruption of an initial pahoehoe surface by a large flux of liquid lava within the flow. In the case of Laki, the lava flux was provided by surges in the erupted effusion rate. At BĂşrfells it appears that the rapid flow came from the sudden breaching of the margins of a large ponded lava flow. Using the observations from Iceland, we have improved our earlier thermal modeling of the Martian flood lavas. We now conclude that these platy-ridged lava flows may have been quite thermally efficient, allowing the flow to extend for >100 km under a disrupted crust that was carried on top of the flow
New <sup>40</sup>Ar/<sup>39</sup>Ar dating of the Grande Ronde lavas, Columbia River Basalts, USA: Implications for duration of flood basalt eruption episodes
Grande Ronde Basalt (GRB) lavas represent the most voluminous eruptive pulse of the Columbia River-Snake River-Yellowstone hotspot volcanism. With an estimated eruptive volume of 150,000 km3, GRB lavas form at least 66% of the total volume of the Columbia River Basalt Group. New 40Ar/39Ar dates for GRB lavas reveal they were emplaced within a maximum period of 0.42 Âą 0.18 My. A well-documented stratigraphy indicates at least 110 GRB flow fields (or individual eruptions), and on this basis suggests an average inter-eruption hiatus of less than 4,000 years. Isotopic age-dating cannot resolve time gaps between GRB eruptions, and it is difficult to otherwise form a picture of the durations of eruptions because of non-uniform weathering in the top of flow fields and a general paucity of sediments between GR lavas. Where sediment has formed on top of the GRB, it varies in thickness from zero to 20-30 cm of silty to fine-sandy material, with occasional diatomaceous sediment. Individual GRB eruptions varied considerably in volume but many were greater than 1000 km3 in size. Most probably eruptive events were not equally spaced in time; some eruptions may have followed short periods of volcanic repose (perhaps 102 to 103 of yrs), whilst others could have been considerably longer (many 1000 s to > 104 yrs). Recent improvements in age-dating for other continental flood basalt (CFB) lava sequences have yielded estimates of total eruptive durations of less than 1 My for high-volume pulses of lava production. The GRB appears to be a similar example, where the main pulse occupied a brief period. Even allowing for moderate to long-duration pahoehoe flow field production, the amount of time the system spends in active lava-producing mode is small â less than c. 2.6% (based on eruption durations of approximately 10,000 yrs, as compared to the duration of the entire eruptive pulse of c. 420,000 yrs). A review of available 40Ar/39Ar data for the major voluminous phases of the Columbia River Basalt Group suggests that activity of the Steens Basalt-Imnaha Basalt-GRB may have, at times, been simultaneous, with obvious implications for climatic effects. Resolving intervals between successive eruptions during CFB province construction, and durations of main eruptive pulses, remains vital to determining the environmental impact of these huge eruptions
On the design of an energy-efficient low-latency integrated protocol for distributed mobile sensor networks
Self organizing, wireless sensors networks are an emergent and challenging technology that is attracting large attention in the sensing and monitoring community. Impressive progress has been done in recent years even if we need to assume that an optimal protocol for every kind of sensor network applications can not exist. As a result it is necessary to optimize the protocol for certain scenarios. In many applications for instance latency is a crucial factor in addition to energy consumption. MERLIN performs its best in such WSNs where there is the need to reduce the latency while ensuring that energy consumption is kept to a minimum. By means of that, the low latency characteristic of MERLIN can be used as a trade off to extend node lifetimes. The performance in terms of energy consumption and latency is optimized by acting on the slot length. MERLIN is designed specifically to integrate routing, MAC and localization protocols together. Furthermore it can support data queries which is a typical application for WSNs. The MERLIN protocol eliminates the necessity to have any explicit handshake mechanism among nodes. Furthermore, the reliability is improved using multiple path message propagation in combination with an overhearing mechanism. The protocol divides the network into subsets where nodes are grouped in time zones. As a result MERLIN also shows a good scalability by utilizing an appropriate scheduling mechanism in combination with a contention period
2014/15 Skills2Play/Sport programme evaluation
The Primary School Physical Literacy Framework reflects the importance of the development of childrenâs physical literacy; âthe motivation, confidence, knowledge and understanding that provides children with the movement foundation for lifelong participation in physical activity.â It also provides clear guidance as to how schools can maximise opportunities to develop the physical literacy of their pupils. Skills2Play and Skills2PlaySport are two complementary primary school physical literacy initiatives designed to support the objectives of the new Framework. Together they comprise the Skills2Play/Sport programme. Throughout this report the term Skills2Play/Sport refers to the programme, comprising both initiatives (Skills2Play and Skills2PlaySport). The programme consists of training and a resource and equipment package, which includes activity cards for both Skills2Play (blue cards) and Skills2PlaySport (purple cards) supplied to primary school deliverers by the Youth Sport Trust. Skills2Play is targeted at Key Stage 1 (KS1) and focuses on generic skill development through a range of play activities that focus on stability, object control and locomotion. Skills2PlaySport is targeted at lower Key Stage 2 (KS2) and includes multiskill activities that build from the generic skills but also introduce the connectivity with the sports through the development of skills specific to sporting âthemesâ, namely âInvasionâ, âStriking and Fieldingâ and âNet/Wallâ. Further themes are currently at varying stages of development and include âAquaticsâ, âGymnasticsâ, âAthleticsâ and âWheelsâ.
ABOUT THE EVALUATION
The Centre for Sport, Physical Education & Activity Research (SPEAR) was commissioned by the Youth Sport Trust to conduct an independent evaluation of the Skills2Play/Sport programme between January 2014 and July 2015. The initial stages of the evaluation focused on the pilot programme undertaken in fifty primary schools. In May 2014 SPEAR produced the Pilot Evaluation Report, which captured teachersâ experiences of the training, resources and delivery of the Skills2Play/Sport pilot programme. The programme was then rolled out to 1,000 schools nationally and the objectives of the Evaluation of the national Skills2Play/Sport programme were as follows:
1. To assess how Skills2PlaySport and Skills2Play are being delivered and sustained in primary schools to support childrenâs physical literacy development.
2. To investigate the impact of Skills2PlaySport on the development of lower Key Stage 2 childrenâs physical literacy over 12 weeks of the programme.
3. To investigate the impact of Skills2Play on the development of Key Stage 1 childrenâs physical literacy over 12 weeks of the programme
Engineering geology of British rocks and soils : Lias Group
The report begins with an introduction and a detailed modern assessment of the geology of the
Lias Group in terms of both stratigraphy and lithology. The modern lithostratigraphy is placed in
the context of the old, and sometimes more familiar, usage. The next two chapters deal with the
mineralogy of a suite of samples collected for the project, and an assessment of the nature and
influence of weathering based on a detailed analysis of the Lias dataset held in the BGS National
Geotechnical Properties Database. The following chapters cover geohazards associated with the
Lias Group, and a brief overview of the wide variety of industrial applications for which the Lias
is well known. The geotechnical database forms the basis of the penultimate chapter,
geotechnical properties. The contents of the database are analysed, interpreted, presented in
graphical form, and discussed in terms of statistical variation and in the light of likely
engineering behaviour. The engineering geology of the Lias Group is discussed in the final
chapter, borrowing from the preceding chapters. A comprehensive cited reference list and a
bibliography are provided. In addition to the large number of technical data provided to BGS, a
small data set has been generated by BGS laboratories, particularly in areas where the main
database was deficient, and also in connection with associated BGS studies of the swelling and
shrinkage properties of the Lias Group.
The individual items of data making up the database are not attributed. However, the
contribution of a wide range of consultancies, contractors, authorities, and individuals is
acknowledged. It is hoped that this report will provide a source of useful information to a wide
range of engineers, planners, scientists, and other interested parties concerned with Lias Group
materials.
It should be noted that whilst quantitative technical data are included in this report, these should
not be used as a substitute for proper site investigation
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