Ball, JE & Williams, BJ 1984, 'Characteristic schemes using fixed spatial grids.'.
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Characteristic schemes for the solution of the Saint Venant equations for unsteady flow in a fixed bed prismatic open channel without lateral inflow were examined. The study was restricted to schemes using a fixed spatial grid requiring interpolation between the characteristics and the grid. Five solution techniques which differed in their interpolation procedure and order of finite difference approximation were developed. The accuracy of the water level and flow rate predicted by each solution technique for different grid spacing were compared and mass balances were computed for each technique. (A)
Debroy, A, Nandy Mazumdar, S, Barua, PD & Mahajan, MP 1984, 'Desulfurization of N,N′-Diarylthioureas by Lead Tetraacetate Oxidation', Bulletin of the Chemical Society of Japan, vol. 57, no. 1, pp. 315-316.
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Abstract Lead tetraacetate oxidation of N,N′-diarylthioureas in refluxing dichloromethane and pyridine gave the corresponding N,N′-diarylureas. Sulfur was isolated during each oxidation reaction.
Miyanaga, Y, Miki, N & Nagai, N 1984, 'ARMA digital lattice filter based on a linear prediction theory', Electronics and Communications in Japan (Part I: Communications), vol. 67, no. 10, pp. 30-38.
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AbstractThis paper proposes some elementary sections of an ARMA lattice filter. an ARMA lattice filter with an arbitrary AR order and an arbitrary MA order is presented. A conventional ARMA lattice filter has already been constructed by a method used to develop an AR lattice filter to a 2‐dimensional filter. Therefore the conventional filter is not suitable for a filter realization when an AR order and an MA order differ from each other, and for the design of a minimum realized ARMA model. the most important characteristic of lattice filters is an orthogonality between every prediction error calculated at each elementary section. Employing this characteristic, we employ the AR lattice filter in a speech analysis, synthesis, an equalizer, and so on. It is shown that the proposed ARMA lattice filter satisfies an orthogonality. Furthermore, the ARMA lattice inverse filter which is an analyzer for an observed waveform and the ARMA lattice filter which is a synthesizer for the waveform are presented.
Svirezhev, YM, Krysanova, VP & Voinov, AA 1984, 'Mathematical modelling of a fish pond ecosystem', Ecological Modelling, vol. 21, no. 4, pp. 315-337.
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Vigneswaran, S & Mazumdar, B 1984, 'Intermixing of media in dual media filters', Effluent & Water Treatment Journal, vol. 24, no. 9, pp. 341-345.
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Though many theoretical formulations exist to determine the size ratio of anthracite to sand grains which cause mixing in dual media filters, there is no specific means to quantify the degree of mixing with variation of size ratio. This suggests a method of quantifying the degree of mixing, and attempts to determine the effect of intermixing on effluent quality and headloss development. A mathematical model has been formulated to explain the observed experimental results.
Vigneswaran, S & Thiyagaram, M 1984, 'Application of filtration theories to ground water recharge problems', Water, Air, and Soil Pollution, vol. 22, no. 4, pp. 417-428.
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A mathematical model is formulated for filtration of different flow conditions (radial flow, spherical flow and combined radial and vertical downwards flow) from O'Melia's model for deep bed filtration. The simple ground water recharge problems with the above mentioned flow conditions are also presented. The radial flow mathematical model was verified using bench-scale radial flow experiments. The removal efficiency and headless in spherical flow and combined radial - vertical downwards flow models with equal bed volume were simulated. © 1984 D. Reidel Publishing Company.
Vigneswaran, S, Notthakun, S & Thanh, NC 1984, 'Flocculation time optimization in direct water filtration', Effluent & Water Treatment Journal, vol. 24, no. 7, pp. 270-274.
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Direct filtration consists of unit operations without the use of sedimentation. Past experiences indicate that this is an economical solution for low turbid waters. A laboratory-scale experimental study has been carried out to see the effects of flocculation gradient, flocculation time and coagulant dose on direct filtration performance. The results indicated that there exists a threshold flocculation time for which filtration run lengths are longest and that this threshold increases with decrease in alum dose and flocculation gradient. The determination of the threshold flocculation time for the water to be treated from a laboratory-scale direct filtration study, therefore, would lead to an optimal solution for direct filtration. 19 refs.
Vigneswaran, S, Visvanathan, C & Ben Aim, R 1984, 'Optimization of sand recycle rate in mobile bed filtration', Effluent & Water Treatment Journal, vol. 24, no. 12, pp. 457-460.
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Rapid sand filters have been used as a final clarifying step in municipal water treatment plants since the early 1900's. The mobile-bed deep filter process uses compressed air to lift and separate retained particles in the sand. Although reports indicate that this type of filter operates continuously without any problem, sand recycling was found to be an energy consuming process. It is therefore essential to optimize the sand recycle rate. In this study the optimum recycle rate for a particular filtration rate was estimated from the 'filter clogging front theory' using fixed bed experimental results.
Voinov, AA & Svirezhev, YM 1984, 'A minimal model of eutrophication in freshwater ecosystems', Ecological Modelling, vol. 23, no. 4, pp. 277-292.
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Watanabe, H, Miyanaga, Y, Miki, N & Nagai, N 1984, 'CONSTRUCTION OF STABLE REDUCED-ORDER ARMA MODEL.', Electronics & communications in Japan, vol. 67, no. 3, pp. 8-17.
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This paper presents a method to construct a stable reduced-order autoregressive and moving-average (ARMA) model using a frequency weighting function. With known ARMA correlation and weighting function, the parameters of the reduced-order ARMA model that minimize the least squares error are found by a solution of a set of normal equations with Toeplitz structure. Fast algorithms for solving this normal equation for the ARMA parameters are already shown as the order update recursion. Stabilization algorithms are used if the calculated AR parameters are not stable.
Ball, JE & Williams, BJ 1970, 'CHARACTERISTIC SCHEMES USING FIXED SPATIAL GRIDS.', National Conference Publication - Institution of Engineers, Australia, I.E.Aust. Nat. Conf. Pub. No. 84/7, Barton, Adelaide, Australia, pp. 24-28.
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Characteristic schemes for the solution of the Saint Venant equations for unsteady flow in a fixed-bed prismatic open channel without lateral inflow were examined. The study was restricted to schemes using a fixed spatial grid requiring interpolation between the characteristics and the grid. Five solution techniques which differed in their interpolation procedure and order of finite difference approximation were developed. The accuracy of the water level and flow rate predicted by each solution technique for different grid spacings were compared and mass balances were computed for each technique.
Bone, DJ, Bachor, H-A & Sandeman, RJ 1970, 'Spatially Resolved Measurements of the Ionisation and Excitation in a laser Pumped Barium Vapour', The Third Gaseous Electronics Meeting, Townsville.
Graham, LB & Hadgraft, RG 1970, 'FARM DAM CHANNEL BYWASHES.', National Conference Publication - Institution of Engineers, Australia, pp. 348-352.
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Channel bywashes are side discharge channel spillways, which provide an alternative to conventional farm dam bywashes on steep sites, or where hydraulic problems of very wide bywash outlet widths occur. They do not, however, offer a means of significantly reducing the width of return slope required for a particular project. Analysis of channel bywash flow requires an iterative step solution, using either a computer or powerful programmable calculator. The engineer must judge whether a conventional bywash or channel bywash is appropriate in a particular circumstance.
Roper, H, Baweja, D & Kirkby, G 1970, 'Towards a quantitative measure of durability of concrete structural members', American Concrete Institute, ACI Special Publication, pp. 639-658.
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Brief consideration is given to the uses of a quantitative measure of durability of concrete structural members. A classification scheme of structures, elements, and causes and effects is reviewed by the use of examples. Any quantitative measure of durability of in-situ structural members must be based on data gathered using non-destructive test methods. For any phenomenon such as cracking, corrosion or spalling which influences durability, three factors must be considered, viz. a method of measurement of the phenomenon, the intensity of the phenomenon, and its distribution over the observed area.
Roper, H, Baweja, D & Kirkby, G 1970, 'TOWARDS A QUANTITATIVE MEASURE OF DURABILITY OF CONCRETE STRUCTURAL MEMBERS.', Publication SP - American Concrete Institute, pp. 639-658.
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Brief consideration is given to the uses of a quantitative measure of durability of concrete structural members. A classification scheme of structures, elements, and causes and effects is reviewed by the use of examples. Any quantitative measure of durability of in-situ structural members must be based on data gathered using non-destructive test methods. For any phenomenon such as cracking, corrosion or spalling which influences durability, three factors must be considered, a method of measurement of the phenomenon, the intensity of the phenomenon, and its distribution over the observed area.
