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Wyszukujesz frazę "Wells, R. R." wg kryterium: Autor


Wyświetlanie 1-4 z 4
Tytuł:
Evolution of rill networks on soil - mantled experimental landscapes driven by rainfall and baselevel adjustments
Autorzy:
Gordon, L. M.
Bennett, S. J.
Wells, R. R.
Powiązania:
https://bibliotekanauki.pl/articles/294356.pdf
Data publikacji:
2011
Wydawca:
Stowarzyszenie Geomorfologów Polskich
Tematy:
rill erosion
rill networks
headcuts
simulated rainfall
digital elevation models
Opis:
Experiments were conducted using a soil-mantled flume subjected to simulated rain and downstream baselevel lowering to quantify the evolution of rill networks. Results show that: (1) headcuts formed by baselevel lowering were the primary drivers of rill incision and network development, and the communication of this wave of degradation occurred very quickly through the landscape, (2) rill networks extended upstream by headcut erosion, where channels bifurcated and filled the available space, (3) rill incision, channel development, and peaks in sediment efflux occurred episodically, linked directly to the downstream baselevel adjustments, and (4) sediment discharge and rill drainage density approached asymptotic values with time following baselevel adjustments despite continuous application of rainfall. These findings have important implications for the prediction of soil loss, rill network development, and landscape evolution where headcut erosion can occur.
Źródło:
Landform Analysis; 2011, 17; 57-63
1429-799X
Pojawia się w:
Landform Analysis
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of upstream sediment inflow on headcut morphodynamics
Autorzy:
Wells, R. R.
Bennett, S. J.
Alonso, C. V.
Powiązania:
https://bibliotekanauki.pl/articles/295198.pdf
Data publikacji:
2011
Wydawca:
Stowarzyszenie Geomorfologów Polskich
Tematy:
headcuts
overland flow
simulated rainfall
soil erosion
Opis:
Headcut erosion can severely accelerate soil loss in upland concentrated flows and lead to significant soil degradation in agricultural areas. Previous experimental work has demonstrated that actively migrating headcuts display systematic morphodynamic behavior, and impinging jet theory can provide an excellent theoretical foundation for this erosional phenomenon. This research sought to examine systematically the effect of an upstream sediment inflow on the morphodynamics of actively migrating headcuts in upland concentrated flows. Using a specially designed experimental facility, actively migrating headcuts were allowed to develop, and then subjected to an upstream sediment load composed of sand. As the upstream sediment feed rate increased, the size and migration rate of the headcut decreased markedly, but sediment discharge was less affected. The headcut erosion process was arrested as sediment inflow rates increased above a threshold value. As sediment feed rate upstream of the headcut increased, sediment size fraction downstream of the headcut also increased. This research suggests that headcut erosion can be greatly modulated by an upstream sediment source, further complicating the prediction of soil erosion on upland areas.
Źródło:
Landform Analysis; 2011, 17; 225-227
1429-799X
Pojawia się w:
Landform Analysis
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Did You Have an Impact? A Theory-Based Method for Planning and Evaluating Knowledge-Transfer and Exchange Activities in Occupational Health and Safety
Autorzy:
Kramer, D. M.
Wells, R. P.
Carlan, N.
Aversa, T.
Bigelow, P. P.
Dixon, S. M.
McMillan, K.
Powiązania:
https://bibliotekanauki.pl/articles/90884.pdf
Data publikacji:
2013
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
knowledge transfer and exchange
evaluation
workplace-based research
musculoskeletal disorders
choroby narządów ruchu
ewakuacja
transfer wiedzy bhp
planowanie
badania naukowe
Opis:
Few evaluation tools are available to assess knowledge-transfer and exchange interventions. The objective of this paper is to develop and demonstrate a theory-based knowledge-transfer and exchange method of evaluation (KEME) that synthesizes 3 theoretical frameworks: the promoting action on research implementation of health services (PARiHS) model, the transtheoretical model of change, and a model of knowledge use. It proposes a new term, keme, to mean a unit of evidence-based transferable knowledge. The usefulness of the evaluation method is demonstrated with 4 occupational health and safety knowledge transfer and exchange (KTE) implementation case studies that are based upon the analysis of over 50 pre-existing interviews. The usefulness of the evaluation model has enabled us to better understand stakeholder feedback, frame our interpretation, and perform a more comprehensive evaluation of the knowledge use outcomes of our KTE efforts.
Źródło:
International Journal of Occupational Safety and Ergonomics; 2013, 19, 1; 41-62
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generation and Relaxation of Microstrains in GaN Nanocrystals under Extreme Pressures
Autorzy:
Grzanka, E.
Palosz, B.
Gierlotka, S.
Pielaszek, R.
Bismayer, U.
Janik, J.
Wells, J.
Palosz, F.
Porsch, F.
Powiązania:
https://bibliotekanauki.pl/articles/2035466.pdf
Data publikacji:
2002-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.+w
81.07.Wx
Opis:
Nanocrystalline powders of GaN with grain sizes ranging from 2 to 30 nm were examined under high external pressures by in situ diffraction techniques in a diamond anvil cell at DESY (HASYLAB, Station F3). The experiments on densification of pure powders under high pressure were performed without a pressure medium. The mechanism of generation and relaxation of internal strains and their distribution in nanoparticles was deduced from the Bragg reflections recorded in situ under high pressures at room temperature. The microstrain was calculated from the full-width at half-maximum (FWHM) values of the Bragg lines. It was found that microstrains in GaN crystallites are generated and subsequently relaxed by two mechanisms: generation of stacking faults and change of the size and shape of the grains occurring under external stress.
Źródło:
Acta Physica Polonica A; 2002, 102, 2; 167-174
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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