http://hdl.handle.net/2123/982 2013-05-19T15:56:18Z http://hdl.handle.net/2123/2664 Title: Engineering Ocean Nourishment Authors: Judd, Bruce; Harrison, Daniel P; Jones, Ian S F Abstract: The annual productivity of the ocean is limited by the availability of nutrients. Ocean Nourishment is the concept of purposefully introducing nutrients to the surface ocean to sequester carbon dioxide and increase the sustainable supply of marine protein. The engineering challenges are to inject the nutrients so that they diffuse to an appropriate concentration while being consumed by phytoplankton. Ship based supply of nutrients from onshore manufacture is assumed. Broadcasting granular material onto the surface of the ocean is examined. The depth over which the prills or grains dissolve can be controlled by the diameter and density of the particles. Design considerations are discussed. 2008-07-01T00:00:00Z http://hdl.handle.net/2123/1422 Title: The Economics of CO2 Sequestration Scenarios Using Ocean Nourishment Authors: Jones, Ian S F; Altarawneh, Mohammednoor Abstract: With the aid of a dynamic, general equilibrium model of the global economy, the optimum economic path of carbon dioxide abatement in the atmosphere can be predicted. The “optimum” sequestration path is defined as that which minimizes the economic damage caused by climate change while costing no more than the economic benefits. The prediction depends strongly on the magnitude of the assumed economic damage as a result of climate change. Ocean Nourishment is the purposeful introduction of nutrients into the ocean to sequester atmospheric carbon dioxide and increase the sustainable fish stocks. The feed stock today is natural gas but in the future could be coal. It has been found that carbon credits could be offered to the carbon market at price less $25 (1995 US $) /tonne CO2 avoided, allowing for a typical return on capital and assuming coal prices are stable (in current dollars). The potential of Ocean Nourishment generated carbon credit has been compared with the optimal trajectory carbon tax calculated from different energy models that ignore Ocean Nourishment. This comparison has been done for two emission reduction scenarios, optimum sequestration and Kyoto forever. Following the optimum sequestration path as predicted by the DICE economic model requires about 100 Ocean Nourishment plants to be constructed each decade assuming each plant sequesters 10 Mt of carbon dioxide per year in the ocean. Sensitivity studies show that the number of Ocean Nourishment plants is proportional to the magnitude of the climate change damage function. The Ocean Nourishment option has benefit-cost ratio of 2.75 compared with 1.0 (by definition) of the optimum sequestration. Climate damage to the economy is most severe in the Low Income countries and the economic model has been used to estimate the future cost in this group of countries. Assuming that their population is predetermined, the accumulated economic advantage of mitigating the climate change is $6.2 trillion (1995 US $) accumulated by 2100. The total cost of Ocean Nourishment, is estimated to be $2.5 trillion (1995 US $). The potential of Ocean Nourishment to meet the Kyoto protocol net emissions has also been studied. It has been found that in order to implement a Kyoto forever scenario, about of 150 Ocean Nourishment plants are needed with a total cost much less than the current alternative abatement strategies. Description: 4th Annual conference on Carbon Capture & Sequestration - Developing Potential Paths Forward Based on the Knowledge, Science and Experience to Date. 2005-05-02T00:00:00Z http://hdl.handle.net/2123/1420 Title: Australian-Chinese Ocean Science & Technology - The Proceedings Description: This collection of papers represents The Proceedings of meeting held at the University of Sydney and Australian Academy of Science 15-18 November 2005. 2007-01-22T22:53:34Z http://hdl.handle.net/2123/1086 Title: Underwater acoustic imaging: image due to a specular reflector in the geometrical-acoustics limit. Authors: Blair, David G Abstract: In underwater acoustic imaging, used to produce high-quality images in turbid waters, a specular reflector can produce a 'pseudoimage' of the receiving array at the reflecting surface. Based on the 'geometrical approximation' (similar to geometrical acoustics), formulae are derived for the size and shape of the pseudoimage for both flat and curved reflectors. For curved reflectors, described by two principal radii of curvature, the formulae assume also the 'large-range approximation'. The formulae enable radii of curvature to be determined from an image. Also discussed briefly are possible extensions and the role of non-geometrical effects. Description: Copyright: The Japan Society of Naval Architects and Ocean Engineers. The original publication is available at springerlink.com and directly at http://dx.doi.org/10.1007/s00773-005-0208-z 2006-01-01T00:00:00Z http://hdl.handle.net/2123/1070 Title: Underwater Acoustic Imaging: One-bit Digitisation Authors: Blair, David G; Jones, Ian S F; Madry, Andrew Abstract: In underwater acoustic imaging (UAI), the combination of a two-dimensional (2-D) array and replicate correlation can produce 3-D images, typically of objects at a range of 2 m. A system already developed achieves the high data acquisition rate needed through one-bit sampling (sensing only the sign of the received signal). Noise added before the one-bit sampling avoids the production of 'ghosts' in the image. By simulation and mathematical analysis, the effects of one-bit and added noise are studied for a chirp signal, with a restriction so far to 1-D images (image amplitude versus range). Conditions are given for the avoidance of ghosts and the minimisation of 'image noise' - noise in the image due to one-bit and added noise. A model of image noise is proposed, which is corroborated by the tests carried out to date. A general formula for the root-mean-square image noise is obtained. It has previously been suggested that filtering the singal after sampling would improve the image. However, it is shown that filtering is unnecessary and indeed makes the image worse. It is shown that a strong target can suppress evidence of a weak target because, when the strength of the return signal is raised, essentially the amplitude of the added noise must be raised to avoid 'ghosts'. A general formula, giving the ratio of target strengths such that the weak target has a 50% probability of detection, is obtained. 2006-08-17T05:28:57Z http://hdl.handle.net/2123/986 Title: Engineering Carbon Sequestration in the Ocean Authors: Jones, Ian S F; Lu, Chien Hsing 2003-05-01T00:00:00Z