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  • Nature Publishing Group  (29)
  • National Academy of Sciences  (28)
  • Oxford University Press  (28)
  • Blackwell Publishing Ltd  (24)
  • Cambridge University Press  (24)
  • Public Library of Science (PLoS)
  • 2000-2004  (60)
  • 1980-1984  (73)
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  • 1
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    Water wave scattering by a step of arbitrary profile (2000)
    Cambridge University Press
    Details
    Publication Date: 2000-05-25
    Description: The two-dimensional scattering of water waves over a finite region of arbitrarily varying topography linking two semi-infinite regions of constant depth is considered. Unlike many approaches to this problem, the formulation employed is exact in the context of linear theory, utilizing simple combinations of Green's functions appropriate to water of constant depth and the Cauchy-Riemann equations to derive a system of coupled integral equations for components of the fluid velocity at certain locations. Two cases arise, depending on whether the deepest point of the topography does or does not lie below the lower of the semi-infinite horizontal bed sections. In each, the reflected and transmitted wave amplitudes are related to the incoming wave amplitudes by a scattering matrix which is defined in terms of inner products involving the solution of the corresponding integral equation system. This solution is approximated by using the variational method in conjunction with a judicious choice of trial function which correctly models the fluid behaviour at the free surface and near the joins of the varying topography with the constant-depth sections, which may not be smooth. The numerical results are remarkably accurate, with just a two-term trial function giving three decimal places of accuracy in the reflection and transmission coefficients in most cases, whilst increasing the number of terms in the trial function results in rapid convergence. The method is applied to a range of examples.
    Print ISSN: 0022-1120
    Electronic ISSN: 1469-7645
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Cambridge University Press
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  • 2
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    Scattered and free waves over periodic beds (2003)
    Cambridge University Press
    Details
    Publication Date: 2003-05-25
    Description: The behaviour of water waves over periodic beds is considered in a two-dimensional context and using linear theory. Three cases are investigated: the scattering of waves by a finite section of periodic topography; the Bloch problem for infinite periodic topography; and sloshing motions over periodic topography confined between vertical boundaries. Connections are established between these problems. A transfer matrix method incorporating evanescent modes is developed for the scattering problem, which reduces the computation to that required for a single period, without compromising full linear theory. The problem of the existence of Bloch waves can also be posed on a single period, leading to a close relationship between it and the scattering problem. Sloshing motions over periodic beds, which may be regarded as special cases of the Bloch problem, are also found to have a significant connection with wave scattering. Integral equations methods allied to the Galerkin approximation are used to resolve the three problems numerically. In particular, the full linear solution for Bragg resonance is presented, allowing the accuracy of existing approximations to this phenomenon to be assessed. The selection of results given illustrates the main features of the work.
    Print ISSN: 0022-1120
    Electronic ISSN: 1469-7645
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Cambridge University Press
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  • 3
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    Approximations to wave scattering by an ice sheet of variable thickness over undulating bed topography (2004)
    Cambridge University Press
    Details
    Publication Date: 2004-06-25
    Description: An investigation is carried out into the effect on wave propagation of an ice sheet of varying thickness floating on water of varying depth, in three dimensions. By deriving a variational principle equivalent to the governing equations of linear theory and invoking the mild-slope approximation in respect of the ice thickness and water depth variations, a simplified form of the problem is obtained from which the vertical coordinate is absent. Two situations are considered: the scattering of flexural-gravity waves by variations in the thickness of an infinite ice sheet and by depth variations; and the scattering of free-surface gravity waves by an ice sheet of finite extent and varying thickness, again incorporating arbitrary topography. Numerical methods are devised for the two-dimensional versions of these problems and a selection of results is presented. The variational approach that is developed can be used to implement more sophisticated approximations and is capable of producing the solution of full linear problems by taking a large enough basis in the Rayleigh-Ritz method. It is also applicable to other situations that involve wave scattering by a floating elastic sheet. © 2004 Cambridge University Press.
    Print ISSN: 0022-1120
    Electronic ISSN: 1469-7645
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 4
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    Interaction of water waves with three-dimensional periodic topography (2001)
    Cambridge University Press
    Details
    Publication Date: 2001-05-10
    Description: The scattering and trapping of water waves by three-dimensional submerged topography, infinite and periodic in one horizontal coordinate and of finite extent in the other, is considered under the assumptions of linearized theory. The mild-slope approximation is used to reduce the governing boundary value problem to one involving a form of the Helmholtz equation in which the coefficient depends on the topography and is therefore spatially varying. Two problems are considered: The scattering by the topography of parallel-crested obliquely incident waves and the propagation of trapping modes along the periodic topography. Both problems are formulated in terms of 'domain' integral equations which are solved numerically. Trapped waves are found to exist over any periodic topography which is 'sufficiently' elevated above the unperturbed bed level. In particular, every periodic topography wholly elevated above that level supports trapped waves. Fundamental differences are shown to exist between these trapped waves and the analogous Rayleigh-Bloch waves which exist on periodic gratings in acoustic theory. Results computed for the scattering problem show that, remarkably, there exist zeros of transmission at discrete wavenumbers for any periodic bed elevation and for all incident wave angles. One implication of this property is that total reflection of an incident wave of a particular frequency will occur in a channel with a single symmetric elevation on the bed. The zeros of transmission in the scattering problem are shown to be related to the presence of a 'nearly trapped' mode in the corresponding homogeneous problem. The scattering of waves by multiple rows of periodic topography is also considered and it is shown how Bragg resonance - well-established in scattering of waves by two-dimensional ripple beds - occurs in modes other than the input mode.
    Print ISSN: 0022-1120
    Electronic ISSN: 1469-7645
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 5
    Electronic Resource
    Electronic Resource
    HERBICIDES AND TRANSFORMATION PRODUCTS IN SURFACE WATERS OF THE MIDWESTERN UNITED STATES (2003)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 39 (2003), S. 0 
    Details
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : Most herbicides applied to crops are adsorbed by plants or transformed (degraded) in the soil, but small fractions are lost from fields and either move to streams in overland runoff, near surface flow, or subsurface drains, or they infiltrate slowly to ground water. Herbicide transformation products (TPs) can be more or less mobile and more or less toxic in the environment than their source herbicides. To obtain information on the concentrations of selected herbicides and TPs in surface waters of the Midwestern United States, 151 water samples were collected from 71 streams and five reservoir outflows in 1998. These samples were analyzed for 13 herbicides and 10 herbicide TPs. Herbicide TPs were found to occur as frequently or more frequently than source herbicides and at concentrations that were often larger than their source herbicides. Most samples contained a mixture of more than 10 different herbicides or TPs. The ratios of TPs to herbicide concentrations can be used to determine the source of herbicides in streams. Results of a two-component mixing model suggest that on average 90 percent or more of the herbicide mass in Midwestern streams during early summer runoff events originates from the runoff and 10 percent or less comes from increased ground water discharge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1752-1688.2003.tb04402.x
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  • 6
    Electronic Resource
    Electronic Resource
    Characterization of greenbug resistance in barley (2004)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 123 (2004), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The greenbug [Schizaphis graminum (Rondani)] is an extremely damaging pest of barley (Hordeum vulgare L.), particularly in the southern Great Plains of the USA. Winter barley targeted for production in this region should incorporate resistance to greenbug in the form of the resistance gene Rsg1a (in ‘Post 90′) or Rsg2b (in PI 426756). This study was conducted to fully characterize the resistance profile of these two genes against important greenbug biotypes, and to determine which of the two resistance genes is most effective in protecting barley from the greenbug. Eight barley and four wheat cultivars and germplasms were challenged with six greenbug biotypes and damage ratings were recorded for each combination. In five of the six tests, ‘Post 90’ was significantly more resistant than PI 426756 to greenbug feeding damage. Based on the results presented here, we conclude that the resistance gene, Rsg1a, in ‘Post 90’ is the better choice for use in breeding programmes and will provide better protection than Rsg2b against the greenbug.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0523.2004.01019.x
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  • 7
    Electronic Resource
    Electronic Resource
    An Evaluation of Sources of Nitrogen as Causes of Ground-Water Contamination in Nassau County, Long Island (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 18 (1980), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: An evaluation of sources of nitrogen in an urban area indicates that it may be difficult to distinguish effects on the quality of underlying ground water. In Nassau County two principal sources of nitrogen are human waste water and fertilized turf. The effects of these sources, combined with other sources such as domestic animals and precipitation, are such that management of one source, i.e. the removal of waste water via sewers, may be less effective than expected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1980.tb03656.x
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  • 8
    Electronic Resource
    Electronic Resource
    Performance of a Scraped-Surface Heat Exchanger Under Ultra High Temperature Conditions: A Dimensional Analysis (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 47 (1982), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Performance characteristics of a pilot-scale scraped-surface heat exchanger (Contherm Model 6 × 2) under UHT operating conditions were evaluated. Outlet temperature and overall heat transfer coefficient (U) were significantly affected by rotational speed of the blades, mass flow rate of feed, feed inlet temperature, steam pressure and solids content of the model low-acid liquid food (soy extracts). The scraping action of the blades greatly improved the performance up to about 350 rpm; higher blade speeds had little or no effect and sometimes decreased U values. Application of dimensionless models showed that the effect of axial Reynolds number (ReA) on the Nusselt number was more significant in the turbulent regime (ReA 〉 1800), while rotational Reynolds number above 105 had a significant effect at all values of ReA between 1200 and 3700. At very high values of the Taylor number (〉 1010) when laminar axial flow conditions prevailed, Nusselt number decreased with increase in rotational Reynolds number.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1982.tb10136.x
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  • 9
    Electronic Resource
    Electronic Resource
    Phenolic Antioxidants of Soy Protein Hydrolyzates (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 47 (1982), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Soy protein hydrolyzate (SPH) was investigated to identify the phenolic compounds responsible for antioxidant activity. Three isoflavones–genistein, daidzein, and glycitein–were found in SPH. These are the same isoflavones that have been identified in raw soybeans. No isoflavone glycosides were found in SPH. The phenolic acids found in SPH were caffeic, ferulic, p-coumaric, syringic, vanillic, gentisic, and p-hydroxybenzoic acids. The compounds were identified by TLC, GLC and UV spectra. The isoflavones were confirmed by their mass spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1982.tb11018.x
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  • 10
    Electronic Resource
    Electronic Resource
    Temperature, light intensity and plasma melatonin levels in juvenile Atlantic salmon (2001)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 58 (2001), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Plasma melatonin synthesis in juvenile Atlantic salmon Salmo salar decreased with increasing light intensity. Melatonin profiles reflected accurately the photoperiod under which the salmon were maintained. Groups maintained at 12°C showed significantly higher (P 〈 0·01) levels of dark phase plasma melatonin compared with the groups maintained at 4°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.2001.tb02262.x
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