Rift and thrust tectonics associated with a translational block slide, Abbotsford, New Zealand

1986 ◽  
Vol 123 (1) ◽  
pp. 13-25 ◽  
Author(s):  
D. G. Bishop ◽  
R. J. Norris
Keyword(s):  
Large Scale ◽  
Ground Surface ◽  
Failure Surface ◽  
Bedding Plane ◽  
Small Scale ◽  
Trailing Edge ◽  
Cross Sectional ◽  
Thrust Tectonics ◽  
Sudden Decrease ◽  
Translational Block

AbstractThe East Abbotsford translational block landslide failed suddenly on 8 August, 1979, after months and probably years of slowly accelerating movement. A displacement of about 50 m occurred on a bedding plane dipping 7°, about 30 m below ground surface, at or very near the contact between two formations.The complex graben formed around the head of the landslide is a small scale example of extensional (rift) tectonics. A wedge and prism model is developed to fit the geometry, and meet the constraints of preserving the cross-sectional area and stratal length of the beds involved and also to account for the sequential retrogressive failures of the trailing edge of the sliding block.Reconstruction of the failure sequence at the toe shows the compressional zone to be dominated by overthrusting on upward sloping surfaces or ramps, with subsidiary backthrusting and buckling.The energy expended in overthrusting, coupled with the decrease in mass (and hence driving force) resulting from the retrogressive spalling of the trailing edge of the slide block, indicates that the phase of rapid movement was accompanied by a sudden decrease in resistance on the failure surface for a movement of 50 m to have occurred.Both the rift and thrust structures associated with the landslide have large scale tectonic analogues.

Large- and small-scale vortical motions in a shear layer perturbed by tabs

1999 ◽  
Vol 382 ◽  
pp. 307-329 ◽  
Author(s):  
JUDITH K. FOSS ◽  
K. B. M. Q. ZAMAN
Keyword(s):  
Shear Layer ◽  
Pitch Angle ◽  
Large Scale ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Small Scale ◽  
Streamwise Vortices ◽  
Streamwise Vorticity ◽  
Cross Sectional ◽  
Scale Population

The large- and small-scale vortical motions produced by ‘delta tabs’ in a two-stream shear layer have been studied experimentally. An increase in mixing was observed when the base of the triangular shaped tab was affixed to the trailing edge of the splitter plate and the apex was pitched at some angle with respect to the flow axis. Such an arrangement produced a pair of counter-rotating streamwise vortices. Hot-wire measurements detailed the velocity, time-averaged vorticity (Ωx) and small-scale turbulence features in the three-dimensional space downstream of the tabs. The small-scale structures, whose scale corresponds to that of the peak in the dissipation spectrum, were identified and counted using the peak-valley-counting technique. The optimal pitch angle, θ, for a single tab and the optimal spanwise spacing, S, for a multiple tab array were identified. Since the goal was to increase mixing, the optimal tab configuration was determined from two properties of the flow field: (i) the large-scale motions with the maximum Ωx, and (ii) the largest number of small-scale motions in a given time period. The peak streamwise vorticity magnitude [mid ]Ωx−max[mid ] was found to have a unique relationship with the tab pitch angle. Furthermore, for all cases examined, the overall small-scale population was found to correlate directly with [mid ]Ωx−max[mid ]. Both quantities peaked at θ≈±45°. It is interesting to note that the peak magnitude of the corresponding circulation in the cross-sectional plane occurred for θ≈±90°. For an array of tabs, the two quantities also depended on the tab spacing. An array of contiguous tabs acted as a solid deflector producing the weakest streamwise vortices and the least small-scale population. For the measurement range covered, the optimal spacing was found to be S≈1.5 tab widths.

On turbulent separation in the flow past a bluff body

1992 ◽  
Vol 241 ◽  
pp. 443-467 ◽  
Author(s):  
A. Neish ◽  
F. T. Smith
Keyword(s):  
Large Scale ◽  
Bluff Body ◽  
Separated Flow ◽  
Small Scale ◽  
Supporting Evidence ◽  
Turbulent Regime ◽  
Trailing Edge ◽  
Flow Past ◽  
Starting Point ◽  
Turbulence Factor

The basic model problem of separation as predicted by the time-mean boundary-layer equations is studied, with the Cebeci-Smith model for turbulent stresses. The changes between laminar and turbulent flow are investigated by means of a turbulence ‘factor’ which increases from zero for laminar flow to unity for the fully turbulent regime. With an attached-flow starting point, a small increase in the turbulence factor above zero is found to drive the separation singularity towards the trailing edge or rear stagnation point for flow past a circular cylinder, according to both computations and analysis. A separated-flow starting point is found to produce analogous behaviour for the separation point. These findings lead to the suggestion that large-scale separation need not occur at all in the fully turbulent regime at sufficiently high Reynolds number; instead, separation is of small scale, confined near the trailing edge. Comments on the generality of this suggestion are presented, along with some supporting evidence from other computations. Further, the small scale involved theoretically has values which seem reasonable in practical terms.

scholarly journals HONEYBEE PRODUCTION SYSTEM, CHALLENGES AND OPPORTUNITIES IN SELECTED DISTRICTS OF GEDEO ZONE, SOUTHERN NATION, NATIONALITIES AND PEOPLES REGIONAL STATE, ETHIOPIA

2016 ◽  
Vol 4 (4) ◽  
pp. 49-63
Author(s):  
Teklu Gebretsadik ◽  
Dinku Negash
Keyword(s):  
Production System ◽  
Large Scale ◽  
Market Access ◽  
Production Systems ◽  
Skill Training ◽  
Cross Sectional Study ◽  
Small Scale ◽  
Cross Sectional ◽  
Production Constraints ◽  
Regional State

The study was carried out in selected districts of Gedeo zones of southern Nation nationality and people’s regional state: such as Wonago, Kochere and DillaZuria/chichu/ districts. The objective of the study was to asses production systems, opportunities and constraints of apiculture farming in Gedeo zones of SNNPRs. Beekeeping is a long-standing practice in the study districts and appears as ancient history of the country as a whole. A cross sectional study, in which 90 households were purposively included and conducted in selected district to assess the current beekeeping practices, production potentials and production constraints. Most (72%) of the beekeepers in the study area have owned only traditional hives and produce honey for home consumption. The beekeeping practice was dominated by male.  Despite the area have  production constraints, the area opportunities like existence of large sized natural forest and artificial forest, due attention provision from regional, federal and local government and nongovernmental organizations, yearly flowering and variety floral availability, some small scale farmers highly experienced in apiculture farming, market access and high demand of apicultural products at nationally and international level. Therefore, Designing effective honeybee pests and predators controlling methods, Introduction of full package improved beekeeping technologies with adequate practical skill training on all bee keeping trends and queen rearing practices promoting beekeepers important indigenous knowledge, Producing areal major honeybee plants in large scale, Avoiding discarding of bee colonies after honey harvest, Availing the strategies to support farmers with beekeeping business support services, Improving pre- and post-harvest handling of bee products and Improving the utilization of stingless bee’s resources, without damaging the colony is important to make the honey production system in the area more economical, so as to enhance bee products for national and international need.

scholarly journals Neurobehavioural symptoms and acute pesticide poisoning: a cross-sectional study among male pesticide applicators selected from three commercial farming systems in Ethiopia

2018 ◽  
Vol 75 (4) ◽  
pp. 283-289 ◽  
Author(s):  
Beyene Negatu ◽  
Roel Vermeulen ◽  
Yalemtshay Mekonnen ◽  
Hans Kromhout
Keyword(s):  
Large Scale ◽  
Pesticide Exposure ◽  
Farming Systems ◽  
Cumulative Exposure ◽  
Small Scale ◽  
Pesticide Poisoning ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Pesticide Applicators ◽  
Acute Pesticide Poisoning

ObjectiveTo estimate prevalence of acute pesticide poisoning (APP) and its association with neurobehavioural symptoms in Ethiopian pesticide applicators.MethodsWe performed a cross-sectional survey among 256 pesticide applicators from small-scale irrigated farms, a large-scale open farm and large-scale greenhouses. APP was ascertained using a modified WHO case definition, and neurobehavioural symptoms were collected with a standardised questionnaire (Q16). Exposure to pesticides was estimated using detailed exposure algorithms specifically developed for Ethiopian farms. Multiple logistic regression models were used to estimate risk of APP and its association with neurobehavioural symptoms.ResultsOverall APP prevalence was 16%. Working as an applicator in greenhouses was strongly associated with APP (OR 3.00, 95% CI 1.38 to 6.54). Estimated annual pesticide exposure was also associated with APP (OR 1.14, 95% CI 1.00 to 1.20). Longer duration of employment appeared to be negatively associated with APP. Having had an APP was strongly associated with reporting more neurobehavioural symptoms (OR 2.15, 95% CI 1.01 to 4.58) independent of cumulative pesticide exposure. Cumulative exposure to pesticides appeared to be associated with neurobehavioural symptoms among applicators without and with APP.ConclusionsWe showed a substantial prevalence of APP that differed between farming systems and was strongly associated with neurobehavioural symptoms. Intensity of exposure was also clearly associated with these symptoms. Reduction and control of occupational exposure to pesticides is urgently needed in Ethiopia.

scholarly journals Altimetric observations of surface characteristics of the Antarctic ice sheet

1997 ◽  
Vol 43 (144) ◽  
pp. 265-275 ◽  
Author(s):  
Benoît Legrésy ◽  
Frédérique Rémy
Keyword(s):  
Large Scale ◽  
Ice Sheet ◽  
Leading Edge ◽  
Small Scale ◽  
Height Measurement ◽  
Trailing Edge ◽  
Antarctic Ice Sheet ◽  
Linear Effect ◽  
Continental Scale ◽  
The Antarctic

AbstractThe aim of this paper is to investigate the geophysical characteristics of the Antarctic ice sheet using radar altimetric observations. To do this, we use an altimetric waveform simulator, in situ observations, ERS-1 (European remote-sensing satellite) data and SPOT (Satellite pour l’observation de la terre) images. The small-scale study takes place at Dome C, Terre Adélie, which is a relatively flat region with gentle undulations and low wind speed. Despite this, the altimetric waveform parameters (height, energy, leading edge and trailing edge) are highly noisy. The effect of undulations on the waveform parameters is found to be dominant. The combination of a subsurface signal and a rough surface produces a linear effect on the altimetric backscattering or on the trailing edge of the waveform, but a strongly non-linear effect on the leading edge of the waveform or height estimation. As a consequence, the height measurement is very sensitive to the altimeter technical or orbital characteristics and is not reproducible from one mission to another. Observations show sastrugi fields that enhance the leading edge and affect the whole waveform. Observed local backscattering changes, probably due to local variations in surface microroughness, enhance the backscattered energy and may artificially create a topographic signal. The continental-scale study shows coherent patterns. Even if both surface and subsurface components affect the altimetric observation, the large-scale signal is mostly controlled by surface backscattering variations. The surface or near-subsurface characteristics of the snowpack may then be reached by altimetric observations.

scholarly journals Turbulent transport mechanisms in oscillating bubble plumes

2009 ◽  
Vol 633 ◽  
pp. 191-231 ◽  
Author(s):  
MARCO SIMIANO ◽  
D. LAKEHAL ◽  
M. LANCE ◽  
G. YADIGAROGLU
Keyword(s):  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Large Scale ◽  
Small Scale ◽  
Equivalent Diameter ◽  
Minor Effect ◽  
Reynolds Stresses ◽  
Bubble Plume ◽  
Low Velocity ◽  
Cross Sectional

The detailed investigation of an unstable meandering bubble plume created in a 2-m-diameter vessel with a water depth of 1.5 m is reported for void fractions up to 4% and bubble size of the order of 2.5 mm. Simultaneous particle image velocity (PIV) measurements of bubble and liquid velocities and video recordings of the projection of the plume on two vertical perpendicular planes were produced in order to characterize the state of the plume by the location of its centreline and its equivalent diameter. The data were conditionally ensemble averaged using only PIV sets corresponding to plume states in a range as narrow as possible, separating the small-scale fluctuations of the flow from the large-scale motions, namely plume meandering and instantaneous cross-sectional area fluctuations. Meandering produces an apparent spreading of the average plume velocity and void fraction profiles that were shown to remain self-similar in the instantaneous plume cross-section. Differences between the true local time-average relative velocities and the difference of the averaged phase velocities were measured; the complex variation of the relative velocity was explained by the effects of passing vortices and by the fact that the bubbles do not reach an equilibrium velocity as they migrate radially, producing momentum exchanges between high- and low-velocity regions. Local entrainment effects decrease with larger plume diameters, contradicting the classical dependence of entrainment on the time-averaged plume diameter. Small plume diameters tend to trigger ‘entrainment eddies’ that promote the inward-flow motion. The global turbulent kinetic energy was found to be dominated by the vertical stresses. Conditional averages according to the plume diameter showed that the large-scale motions did not affect the instantaneous turbulent kinetic energy distribution in the plume, suggesting that large scales and small scales are not correlated. With conditional averaging, meandering was a minor effect on the global kinetic energy and the Reynolds stresses. In contrast, plume diameter fluctuations produce a substantial effect on these quantities.

scholarly journals Altimetric observations of surface characteristics of the Antarctic ice sheet

1997 ◽  
Vol 43 (144) ◽  
pp. 265-275 ◽  
Author(s):  
Benoît Legrésy ◽  
Frédérique Rémy
Keyword(s):  
Large Scale ◽  
Ice Sheet ◽  
Leading Edge ◽  
Small Scale ◽  
Height Measurement ◽  
Trailing Edge ◽  
Antarctic Ice Sheet ◽  
Linear Effect ◽  
Continental Scale ◽  
The Antarctic

AbstractThe aim of this paper is to investigate the geophysical characteristics of the Antarctic ice sheet using radar altimetric observations. To do this, we use an altimetric waveform simulator, in situ observations, ERS-1 (European remote-sensing satellite) data and SPOT (Satellite pour l’observation de la terre) images. The small-scale study takes place at Dome C, Terre Adélie, which is a relatively flat region with gentle undulations and low wind speed. Despite this, the altimetric waveform parameters (height, energy, leading edge and trailing edge) are highly noisy. The effect of undulations on the waveform parameters is found to be dominant. The combination of a subsurface signal and a rough surface produces a linear effect on the altimetric backscattering or on the trailing edge of the waveform, but a strongly non-linear effect on the leading edge of the waveform or height estimation. As a consequence, the height measurement is very sensitive to the altimeter technical or orbital characteristics and is not reproducible from one mission to another. Observations show sastrugi fields that enhance the leading edge and affect the whole waveform. Observed local backscattering changes, probably due to local variations in surface microroughness, enhance the backscattered energy and may artificially create a topographic signal. The continental-scale study shows coherent patterns. Even if both surface and subsurface components affect the altimetric observation, the large-scale signal is mostly controlled by surface backscattering variations. The surface or near-subsurface characteristics of the snowpack may then be reached by altimetric observations.

scholarly journals Modelling turbulent boundary layer flow over fractal-like multiscale terrain using large-eddy simulations and analytical tools

2017 ◽  
Vol 375 (2091) ◽  
pp. 20160098 ◽  
Author(s):  
X. I. A. Yang ◽  
C. Meneveau
Keyword(s):  
Large Scale ◽  
Wind Farm ◽  
Ground Surface ◽  
Small Scale ◽  
Subgrid Scale ◽  
Mean Velocity ◽  
Roughness Model ◽  
Roughness Elements ◽  
Large Eddy ◽  
Scale Roughness

In recent years, there has been growing interest in large-eddy simulation (LES) modelling of atmospheric boundary layers interacting with arrays of wind turbines on complex terrain. However, such terrain typically contains geometric features and roughness elements reaching down to small scales that typically cannot be resolved numerically. Thus subgrid-scale models for the unresolved features of the bottom roughness are needed for LES. Such knowledge is also required to model the effects of the ground surface ‘underneath’ a wind farm. Here we adapt a dynamic approach to determine subgrid-scale roughness parametrizations and apply it for the case of rough surfaces composed of cuboidal elements with broad size distributions, containing many scales. We first investigate the flow response to ground roughness of a few scales. LES with the dynamic roughness model which accounts for the drag of unresolved roughness is shown to provide resolution-independent results for the mean velocity distribution. Moreover, we develop an analytical roughness model that accounts for the sheltering effects of large-scale on small-scale roughness elements. Taking into account the shading effect, constraints from fundamental conservation laws, and assumptions of geometric self-similarity, the analytical roughness model is shown to provide analytical predictions that agree well with roughness parameters determined from LES. This article is part of the themed issue ‘Wind energy in complex terrains’.

scholarly journals Biosecurity and management practices in different dog breeding systems have considerable margin for improvements

2018 ◽  
Vol 183 (12) ◽  
pp. 381-381 ◽  
Author(s):  
Pierre-Alexandre Dendoncker ◽  
Christel Moons ◽  
Steven Sarrazin ◽  
Claire Diederich ◽  
Etienne Thiry ◽  
...  
Keyword(s):  
Large Scale ◽  
Management Practices ◽  
Post Partum ◽  
Disease Outbreaks ◽  
Cross Sectional Study ◽  
Breeding Systems ◽  
Small Scale ◽  
Cross Sectional ◽  
Different Types ◽  
Dog Breeding

To investigate the current management and biosecurity practices and identify possible differences between different types of breeders, a cross-sectional study was carried out in 102 Belgian dog breeding facilities ranging from small (less than 10 dams on site) to large-scale (more than 50 dams on site or at least 500 puppies sold yearly) breeders. Veterinary prophylactic protocols (ie, vaccination, endoparasite control, ectoparasitic treatments) were highly implemented (91.5 per cent, 92.6 per cent, 42.7 per cent, respectively) across all breeder categories. 13.8 per cent of all visited breeders reported to administer antimicrobials to each female post partum and 10.3 per cent reported to treat all puppies, or at least of one breed, systematically with antimicrobials. Large-scale breeders reported to employ staff more frequently (p<0.01), and appeared to be more familiar with the principles of biosecurity. They reported to apply disinfection (p<0.01) and hygienic measures (p=0.03) across all parts of the facility, and to quarantine newly acquired dogs (p<0.01) more often compared with small-scale breeders. Nonetheless, a moderate knowledge of and use of disinfection was recorded, as was the presence of pet dogs, breaking the compartmentalisation. Results of this study indicate that there is substantial room for improvement in hygiene and disease management across all categories of breeders. The characterisation of different types of dog breeders with respect to biosecurity and management practices is a first step towards improvement of dog husbandry and biosecurity measures. Tailored guidelines should permit breeders to further improve the health of breeding animals and puppies while reducing the risk of infectious disease outbreaks and associated expenses.

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