107,598 research outputs found
Physical modelling of low-cost modifications to the Crump Weir in order to improve fish passage : evelopment of favourable swimming conditions and investigation of the hydrometric effect
Get PDFMore than 350 Crump-type weirs (which are triangular in profile) form part of the
Environment Agency's hydrometric network in rivers across England and Wales.
These weirs operate as effective measurement structures and are useful over a large
flow range. However, they also act as barriers that impede the passage of many
species of coarse fish within their natural habitat.
The primary aim of this research project was to recommend modifcations to Crump
weirs in order to improve fish passage, while still allowing the weirs to fulfll their
hydrometric purpose in a reliable way. It was an additional requirement that any
proposed solution(s) be both practical and achievable at low-cost. This is in contrast
to conventional fish pass solutions, that tend to be expensive, are generally not
hydrometrically rated, and most of which were not designed with coarse fish in
mind.
The method used was a model study conducted in the laboratory, which allowed for
a great number of layouts to be trialled. Laboratory research combined with fish
swimming data provides a basis for projecting successful fish ascents. Brimpton weir
on the River Enborne was chosen as a suitable reference on which to base laboratory
model tests.
The preferred arrangement (termed a `rotated-V' layout) was found to be a series of
baffles located on the downstream slope of the Crump weir. These baffles effectively
act as weirs at low
flows and roughness elements at high
flows. Each baffle has a
slot which helps to form a path of ascent for fish. The base closest to the crest was
set at the same height as the crest, as this led to optimum low velocities in the slots
on the downstream slope.
Extensive testing revealed that the proposed solution results in a change in a weir's
hydrometric characteristics. However, it was demonstrated that the deviation of the
coefficient of discharge is predictable. Therefore, it allows for reliable
flow measure-
ment to be achieved (subject to a standardised calibration trial using volumetric
flow
measurement techniques). In addition, a detailed measurement and analysis of wa-
ter velocities within the recommended solution strongly suggest that it substantially
improves on the fish passage capability of a Crump weir
Breach Flow Modeled as Flow over a Weir
No full textThe main objective of the study is to understand the effects of breach properties (e.g. the top width, the depth and the bottom width of the breach) on the breach flow. The breach flow was modeled as flow over a compound broad-crested weir. A laboratory experiment was carried out with a fixed weir model in a flume. Five cases with different breach properties were tested. Firstly, the discharge coefficients for all cases were quantitatively determined. The calibrations were done under two flow conditions, namely emerged flow conditions (flow only through the breach) and overtopping flow conditions (flow through the compound cross-section of weir). In perfect weir situations, it turned out that the values of the discharge coefficient were below 1 and rather different in the two flow conditions. Particularly in the case of overtopping flow, the linear combination of traditional discharge equations was verified for predicting the discharge and the discharge distribution over the weir. In imperfect weir situations, submergence coefficient was introduced in emerged condition. Secondly, the dependence of the energy head loss caused by the weir on the upstream discharge and the downstream water depth was discussed in imperfect weir situations. The Form Drag model for estimating the energy head loss was proved to be applicable for the modeled breach flow. Thirdly, the local hydraulic characteristics of breach flow were described by means of velocity distribution, water level elevation and flow patterns appearing behind the weir. At last, the numerical model (Delft3D) was verified on the modeling of the present experiment by comparing with the experimental data. The report provides the information for the breach flow which can be of use in the development of breach models, inundation models and compound weir design.Environmental Fluid DynamicsHydraulic EngineeringCivil Engineering and Geoscience
Breach Flow Modeled as Flow over a Weir
Get PDFThe main objective of the study is to understand the effects of breach properties (e.g. the top width, the depth and the bottom width of the breach) on the breach flow. The breach flow was modeled as flow over a compound broad-crested weir. A laboratory experiment was carried out with a fixed weir model in a flume. Five cases with different breach properties were tested
Audience manipulation? Subverting the fourth wall in Pina Bausch’s Kontakthof (1978) and Nelken (1982)
No full textPina Bausch’s Tanztheater breaks everyday behaviour into its most elemental fragments, and fundamental aspects of stage etiquette are constantly challenged, not least the barrier between performer and spectator known as the fourth wall. Accordingly, the hierarchy of the theatre space is thrown into question, and the audience’s preconceived notions of boundaries, appropriate behaviour and expectations are left open ended. In the following article, two case study examples of Bausch’s works—Kontakthof (‘Meeting Place’, 1978) and Nelken (‘Carnations’, 1982)—have been selected in order to demonstrate the range of techniques Bausch employs in manipulating the fourth wall. Both are lengthy in duration and extremely complex, layered works of dance theatre, illustrating Bausch’s varied methods of audience manipulation at what I have identified as a ‘golden period’ in her career. This article explores the process of audience manipulation through Bausch’s peripatetic use of the fourth wall, illustrating that, as dance theatre has evolved, the performance event has become increasingly confrontational and direct, engaging with the audience in a more provocative manner, and calling into question the limits of the theatre space.Publisher PD
Pursell House (Koonga Maya)
No full textResearch Background\ud
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Bushfire safety and biodiversity conservation are typically considered to be opposing management goals in the world’s bushfire prone landscapes. Although this problem is of national and international significance there are very few researchers or practitioners seeking to reconcile these opposing goals through innovative building design. The Pursell House (Koonga Maya) is sited within Proteaceae dominated shrubland on the south coast of WA known as ‘Kwongkan’, which is recognized internationally for its biodiverse endemism. Indeed since 2015, clearing of Kwongkan has been prohibited under Australia’s Environmental & Biodiversity Conservation Act. \ud
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Research Contribution\ud
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The Pursell House is designed for an extreme Bushfire Attack Level of BAL 40/FZ as per the Australian Standard AS3959:2009. With a very small footprint of 36m2 this house celebrates the rich biota of its site by prioritising bushfire resilience over vegetation management as the primary bushfire risk mitigation strategy. In detail, the project utilises a fire proof ‘exoskeleton’ of cast in-situ concrete that supports novel bushfire shutter designs that are the result of the author’s industrial design innovations. \ud
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Research Significance\ud
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Through the Pursell House, the author has established not only an exemplar for sustainable development in bushfire prone areas but a new field of design research which challenges conventional paradigms that the management goals of biodiversity conservation and bushfire safety are in direct opposition
Simplicity in complexity – towards a soft matter physics of caramel
No full textCaramel is a mixture of sugars, milk proteins, fat and water cooked at high temperatures to initiate Maillard reactions. We study caramels as ‘active emulsion-filled protein gels’, in which fat droplets are chemically-bonded to a background gel matrix of cross-linked proteins in a concentrated aqueous sugar solution. We delimit a ‘caramel region’ in composition space. Oscillatory rheology within this region reveals that we can superpose the mechanical spectra of our caramels into a single pair of G'(w);G''(w) master curves using time-composition superposition (tCS) over 12 decades of frequency, so that these caramels are instances of an underlying ‘universal material’. This insight constrains the molecular mechanisms for structure formation, and implies that measuring a couple of parameters suffices to predict the rheology of caramels over 12 orders of magnitude in frequency
Inflatable weir hydraulics
Get PDFThesis (MEng)--Stellenbosch University, 2015.ENGLISH ABSTRACT: General objective of the study
This thesis aims to evaluate the hydraulics of an inflatable weir in its fully inflated position to the almost fully deflated position using different diameter circular weirs with varying discharges, by considering the change in the weir radius and the dynamic pressures on the weir. In the evaluation, three cylindrical weirs were installed in a 2m wide flume and tested over various discharges.
Methodology
The three weirs, one with a 300mm diameter, another with a 250mm diameter, and the last one with a 100mm diameter, were used to determine the effects of over flow water on the weir as seen in the different stages of the normal operation of an inflatable weir. Simulation involved measurement of the upstream and downstream water levels with the weir height involved at stable over flow conditions. Measurement of pressure variations was done on the weir faces with different water inflow rates to the test flume with three pressure sensors installed on each weir at 0°, 11.25° and 22.5° from the crest to the downstream. Additionally a single 0.15m radius weir was tested for pressures 67.5°, 78.75° and 90° from weir crest. Water level variation on the downstream of the weir was created by means of a variable tail gate to observe its effects.
Results of the investigation
The effects of upstream arches, stage, radius of curvature, discharge, pressure, energy losses over the weir and the downstream hydraulic jump were investigated in the inflation and deflation of the inflatable weir. The findings were as follows:
►Based on literature by Chanson and Montes (1998), Shabanlou et al. (2013), Schmockeret al. (2011) and Bahzad et al. (2010), upstream arches have insignificant influence onthe performance of the inflatable weir. There is rather reduced afflux due to the shape ofthe upstream of the weir from the Bernoulli’s equation. This shape of the upstream of theweir also contributes to the transport of sediments Gebhardt et al. (2012). ►Investigation of the discharge coefficient and factors influencing showed that: oAs the weir radius is reduced during the deflation, the unit discharge over each weirincreased with increase in head above the crest.
oDischarge coefficient of the inflatable weir increases with the increase in head aboveweir crest, and the discharge coefficient is inversely proportional to the radius ofcurvature of the weir.
►Investigation of pressures on the downstream face of the weir models showed that:
oThe negative (suction) pressure acting on the downstream face of the weir becomesincreasingly negative with increase in H/R values.
oPoint of separation of nappe was seen with pulsations of pressure of the recordpressure.
Generally, energy dissipation over the weir decreases with the decrease in the weir radius and the jump is more stable with the smallest circular weir and can be more accurately determined in the case of a small weir.
Conclusions and Recommendations
The inflatable weir has a high discharge at its fully inflated position. Its hydraulic performance is largely influenced by inflow head and is inversely proportional to the radius of curvature. Nappe pulsation as seen in the nappe vibrations can cause the vibration of weir.
Future research on inflatable weirs should aim to monitor the negative pressure on measuring pressures further down the face of the weir because larger negative pressures are expected to develop after 90˚ as with this study
Population differences in immune responses to Bacille Calmette-Guérin vaccination in infancy.
Get PDFBacille Calmette-Guérin (BCG) vaccination induces a marked increase in the interferon (IFN)-gamma response to Mycobacterium tuberculosis purified protein derivative (Mtb PPD) in UK adolescents, but not in Malawian adolescents. We hypothesized that Mtb PPD-induced IFN-gamma after BCG vaccination would be similar in infants from these 2 countries. Infants were vaccinated with BCG during the first 3-13 weeks of life. Three months after BCG vaccination, 51 (100%) of 51 UK infants had an IFN-gamma response to Mtb PPD, compared to 41 (53%) of 78 of Malawian infants, in whom responses varied according to their season of birth. We conclude that population differences in immune responses after BCG vaccination are observed among infants, as well as among young adults
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