1,996 research outputs found
Complex Adaptive System Modelling of River Murray Salinity Policy Options
No full textThis paper reports on complex adaptive system (CAS) simulation of the River Murray Basin in Australia to compare capacity of institutional options to maintain functioning of key river system within a "bandwidth" that limits irreversible system state changes and highly adverse consequences. The modelling framework characterise diverse irrigation agents who profit from water diversion and cause external salinity impacts, water and salt process that form the link between irrigator actions and agricultural profits and external costs, and a river manager who sets institutional rules. Emphasis is on the CAS nature of the system and on institutional rules to accommodate choosing actions differently based on con dition of the system has been referred to as state contingent management (Wills, 2003) or threshold based management (Roe and Van Eeten, 2001). Key findings are that policy focus on the source of salinity by reducing drainage are much more cost effective than strategies to mitigate salinity once it occurs and that state contingent dilution provision when it has high benefit and low opportunity cost is also a cost effective way to manage salinity.Resource /Energy Economics and Policy,
Reducing the cost of South Australia of achieving agreed salinity targets in the River Murray.
No full textPast irrigation development has lead to rising salt loads in the River Murray and its floodplains, and reduced river flows. Even in the absence of any further development, river and floodplain salt loading as the result of this irrigation is anticipated to grow over the decades. Any new development will bring additional salinity loads and further reduced River flows.Australia;river;salinity
A large mid-Holocene estuary was not present in the lower River Murray, Australia
No full textRecent research has suggested that during the mid-Holocene (c. 8500 to 5000 cal yr BP) a large estuary occupied the lower River Murray and its terminal lakes (Lakes Alexandrina and Albert: herein the Lower Lakes) in South Australia. This research has questioned both reconstructions of past River Murray discharge and contemporary environmental water provisions aimed at maintaining the freshwater state of the Lower Lakes. We show that (1) a large mid-Holocene estuary extending into the lower River Murray was not physically possible, and (2) that the River Murray and Lower Lakes were predominantly fresh during the mid-Holocene. Sea level was well below present at the time of purported initiation of estuarine sedimentation and, therefore, could not have allowed formation of an estuary. Holocene human occupation of the lower River Murray valley, that was reliant on freshwater resources, negates the existence of a large estuary in the valley. A variety of freshwater indicators in sediments from in, and around, the Lower Lakes negate the notion of significant marine incursion. Hence, current management of the Lower Lakes as freshwater ecosystems is consistent with their Holocene history.J. Tibby, B. Bourman, C. Wilson, L. M. Mosley, A. P. Belperio, D. D. Ryan ... et al
AMS 14C dating of Holocene estuarine deposits: consequences of high energy and reworked foraminifera
No full textBenthic foraminiferal species were used to AMS date Holocene sediments adjacent to trangressive overlap boundaries (TOB) in two high-energy estuaries in northern Spain. It had previously been recognized that the foraminifera could be divided into indigenous and exotic components. Whereas it was known that the exotic forms had been transported into the estuaries from the adjacent inner shelf, it was assumed that the indigenous forms were in situ. The AMS dates based on indigenous forms obtained from pairs of samples adjacent to the TOB showed an inverse relationship in three out of four boreholes (i.e., the age of the higher sample was older than that of the lower). The most probable explanation of this unexpected result is that there had been significant reworking of indigenous foraminifera especially associated with the transgressive episode. It is concluded that, in high energy estuaries, AMS dating on foraminiferal shells is influenced by transport and reworking even of the indigenous component. Therefore, if only foraminifera are available for dating, we recommend that closely spaced pairs of samples should be dated in order to assess the reliability of the results
Weighted RED (WTRED) strategy for TCP congestion control
No full textThis work presents the Weighted Random Early Detection (WTRED) strategy for congestion handling in TCP networks. The strategy dynamically adjusts RED's maximum threshold, minimum threshold and weight parameters to increase network performance. This work describes RED and FRED implementations and highlights their disadvantages. Using the NS-2 simulator, we compare WTRED with these classic congestion control strategies. The simulation results demonstrate the shortcomings of RED and FRED. The results also show that WTRED achieves greater link utilization and throughput than RED and FRED
The turbulent dissipation rate from PIV measurements
No full textThe result of a particle-image velocimetry (PIV) measurement is a velocity field averaged over interrogation windows. This severely affects the measurement of small-scale turbulence quantities when the interrogation window size is much larger than the smallest length scale in turbulence. A direct measurement of the dissipation rate demands the measurement of gradients of the velocity field, which are now underestimated because the small-scale motion is not resolved. A popular procedure is to relate the statistical properties of the measured, but underresolved gradients to those of the true ones, invoking a large-eddy argument [3]. We show that the used proportionality constant, the Smagorinsky constant, should depend on the window overlap, on the used elements of the strain tensor, and on the way in which derivatives are approximate
How the dispersion of a droplet cloud depends on its initial size
No full textA cloud of droplets evolves under the influence of strong turbulence. The droplets are made from a phosphorescent fluid. From this cloud we select at t = 0 a narrow line by exciting the droplets with a UV laser, which causes them to glow for a few milliseconds. The dispersion of this line is followed in time using a fast intensified camera. A large range of droplet sizes (Stokes number St) was measured. It appears that lines with St \approx 1 disperse faster than a line of fluid tracers. Lines of droplets which are narrowest initially, spread fastest
Reverend William M. Paden, D.D.
No full textThis photograph is a portrait, featured in a publication, of Reverend William M. Paden, D.D. He is wearing a dark suit, light shirt, and a dark tie with polka dots. His hair is parted in the middle and he wears a mustache. He is also wearing wire-rimmed glasses. The background is a medium gray shade.The photograph is in good condition, except for a slight wrinkle in the bottom right corner. On the back the paper appears torn because of glue and there is a small pink spot in the bottom half of the photograph. The following text is printed at the bottom of the photograph: "Reverend William M. Paden D.D. Beloved, purposeful, Missioner of Good Cheer. Leader of Presbyterianism in Utah for thirty-four years, as Pastor, Executive, Author and Counselor. Together by the grace of God, we enter the forward-looking years, growing ever richer in Christian faith and service." The Archives, Giovale Library, Westminster College, has a collection of materials authored by William Paden and also materials about him. Additional biographic information about Dr Paden is available in: Brackenridge, R. Douglas. Westminster College of Salt Lake City. Logan, Utah: Utah State University Press, 1998, pp. 118, 121, 124, 140
On fully nonlinear CR invariant equations on the Heisenberg group
No full textAbstractIn this paper we provide a characterization of second order fully nonlinear CR invariant equations on the Heisenberg group, which is the analogue in the CR setting of the result proved in the Euclidean setting by A. Li and the first author in Li and Li (2003) [21]. We also prove a comparison principle for solutions of second order fully nonlinear CR invariant equations defined on bounded domains of the Heisenberg group and a comparison principle for solutions of a family of second order fully nonlinear equations on a punctured ball
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