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  • 551.9
  • modelling
  • Springer  (25)
  • American Chemical Society (ACS)
  • Blackwell Publishing Ltd
  • 1985-1989  (25)
Collection
Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    A conceptual model for initial and residual responses to phosphorus fertilizers (1985)
    Springer
    Nutrient cycling in agroecosystems 6 (1985), S. 131-138 
    Details
    ISSN: 1573-0867
    Keywords: modelling ; phosphorus ; residual value
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A model is formulated to describe the amount of effective phosphorus in soil. For a source that is immediately fully effective only three parameters are required — the amount of effective phosphorus initially present, the proportion of phosphorus remaining effective after each year, and a parameter which determines the lower limit for the amount of effective phosphorus. An extension of the model to sources that release their phosphorus slowly requires one further parameter — the fraction of such phosphorus released each year. The effective phosphorus in soil is then related to yield using the Mitscherlich equation. The model gave a good description of the growth response ofStylosanthes humilis to superphosphate and calcined Christmas Island C-grade phosphate (CCICP) over three years on a red earth at Katherine, N.T. Furthermore, it enabled a quantitative assessment to be made of the residual value of the CCICP that was not achieved in an earlier analysis of the data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01051007
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  • 2
    Electronic Resource
    Electronic Resource
    Mathematical algorithm for effective phosphorus determination in a rice based cropping system (1988)
    Springer
    Nutrient cycling in agroecosystems 18 (1988), S. 57-61 
    Details
    ISSN: 1573-0867
    Keywords: Cropping system ; modelling ; phosphorus ; residual value ; rice based ; sources of P
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A mathematical model similar to the one suggested by Probert [3] is used to calculate effective phosphorus in two rice crops followed by green gram. The effective phosphorus values are then related to dry matter yield, grain yield and phosphorus uptake in the three crops using linear and Mitscherlich equations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01064178
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  • 3
    Electronic Resource
    Electronic Resource
    A modified pharmacokinetic model for platinum disposition in ovarian cancer patients receiving cisplatin (1987)
    Springer
    European journal of clinical pharmacology 33 (1987), S. 67-72 
    Details
    ISSN: 1432-1041
    Keywords: cisplatin ; pharmacokinetics ; modelling ; drug dispositions ; cancer patients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary We have fitted a first-order multicompartment pharmacokinetic model to plasma platinum concentrations measured in nine ovarian cancer patients who received intravenous infusions of cisplatin for 6 h. The time-course of ultrafilterable plasma platinum was similar in all patients studied, and was fitted by a single compartment within the limits of experimental detection. However, the time-course of protein-bound platinum showed marked differences between patients, the differences being explained by distribution to two peripheral compartments. The wide inter-patient variation observed in protein-bound plasma platinum concentrations supports the view that pharmacokinetic modelling should be carried out separately for each patient, since averaging plasma concentrations would have obscured some individual pharmacokinetic characteristics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00610382
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  • 4
    Electronic Resource
    Electronic Resource
    The superstructure of chromatin and its condensation mechanism (1987)
    Springer
    European biophysics journal 14 (1987), S. 307-319 
    Details
    ISSN: 1432-1017
    Keywords: Chromatin ; synchrotron radiation ; ultracentrifugation ; viscosity ; modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Solutions of rat liver and chicken erythrocyte chromatin at different ionic strngths were characterized by synchrotron X-ray solution scattering, ultracentrifugation, density and viscosity measurements. Previous observations on nuclei were extended to rat liver, calf thymus and yeast nuclei. It is shown that with monovalent cations condensation is independent of the nature of the cation whereas with divalent cations there are significant differences related to the preference of base binding over phosphate binding. The consistency of hydrodynamic and scattering results confirm the view that chromatin in solution at low ionic strength has a helix-like superstructure. A survey of X-ray and neutron scattering results in the literature shows that previous interpretations, e.g. in terms of a 10 nm filament, are incompatible with the experimental data at low resolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00254896
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  • 5
    Electronic Resource
    Electronic Resource
    Modelling particle formation and growth in a plasma synthesis reactor (1988)
    Springer
    Plasma chemistry and plasma processing 8 (1988), S. 145-157 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; particle nucleation and growth ; modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A model for particle nucleation and growth in a thermal plasma reactor is discussed. A nondimensional form of the aerosol general dynamic equation is derived under a set of simplifying assumptions which are appropriate to plasma powder synthesis, and the resulting set of equations is solved numerically. The results are converted to dimensional form for the case of iron powder, for which experimental data are available, and for silicon carbide. Calculated particle sizes increase significantly with increasing reactant concentrations and with decreasing cooling rate, although the influence of cooling rate is mainly a residence time effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01016154
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  • 6
    Electronic Resource
    Electronic Resource
    A model of the chemical processes occurring in CF4/O2 discharges used in plasma etching (1986)
    Springer
    Plasma chemistry and plasma processing 6 (1986), S. 205-230 
    Details
    ISSN: 1572-8986
    Keywords: Plasma etching ; gas-phase reactions ; modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A model has been developed in an attempt to explain the chemistry which occurs in plasmas produced in mixtures of CF4 and O2. Emphasis is placed on gas-phase free radical reactions, and the predictions of the model are compared with experimental results. Dissociation rates following electron impact are deduced mainly from experimental observations although relative dissociation rates have been calculated. An important assumption of the model is that CF2 can be produced as a primary dissociation product following electron impact. Furthermore, this process is favored over that producing CF3 by more than a factor of 2. Experimental evidence is presented to support this assumption. Although the model agrees well with experiment on the total amount of fluorine produced, some discrepancy exists between the predicted and measured values of [F2]. It is suggested that the higher concentrations detected in the experiments resulted from recombination of F atoms in the sampling region. The agreement for concentrations of CO2, CO, and COF2 is generally better than a factor of 2 over a wide range of experimental conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00575129
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  • 7
    Electronic Resource
    Electronic Resource
    A model for the etching of Si in CF4 plasmas: Comparison with experimental measurements (1986)
    Springer
    Plasma chemistry and plasma processing 6 (1986), S. 231-246 
    Details
    ISSN: 1572-8986
    Keywords: Plasma etching ; CF4 chemistry ; modelling ; comparison with experiments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A model has been developed to describe the chemistry which occurs in CF4 plasmas and the etching of Si both in the plasma and downstream. One very important feature of this model is that for discharge residence times which vary by more than an order of magnitude, the amount of CF4 consumed is low and relatively constant. This is because the gas-phase combination reactions between F and both CF3 and CF2 lead to the rapid reforming of CF4. The model predicts that CF2 is a major species in the gas phase and that the [F] detected as a sample point downstream is a very sensitive function of [CF2]/[F] in the discharge. Even though the calculations show that [F] in the discharge varies only slightly over the wide range of experimental conditions considered, large variations in [F] at the sample point occur because the [CF2]/[F] ratio in the discharge changes. The concentrations of C2F6 and SiF4 are predicted to within a factor of 2 over a very wide range of experimental conditions. This confirms the importance of gas-phase free radical reactions in the etching of Si.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00575130
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  • 8
    Electronic Resource
    Electronic Resource
    Characterizing optimality in mathematical programming models (1988)
    Springer
    Acta applicandae mathematicae 12 (1988), S. 113-180 
    Details
    ISSN: 1572-9036
    Keywords: 90C25 ; 90C48 ; 90C31 ; 54C10 ; 54C60 ; 49B27 ; 49B50 ; Mathematical programming ; modelling ; optimality conditions ; parameters ; continuity ; point-to-set mappings ; convexity ; optimal value function ; input optimization ; regions of stability ; Lagrangian functions ; input constraint qualifications ; multi-objective optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This paper is a survey of basic results that characterize optimality in single- and multi-objective mathematical programming models. Many people believe, or want to believe, that the underlying behavioural structure of management, economic, and many other systems, generates basically ‘continuous’ processes. This belief motivates our definition and study of optimality, termed ‘structural’ optimality. Roughly speaking, we say that a feasible point of a mathematical programming model is structurally optimal if every improvement of the optimal value function, with respect to parameters, results in discontinuity of the corresponding feasible set of decision variables. This definition appears to be more suitable for many applications and it is also more general than the usual one: every optimum is a structural optimum but not necessarily vice versa. By characterizing structural optima, we obtain some new, and recover the familiar, optimality conditions in nonlinear programming. The paper is self-contained. Our approach is geometric and inductive: we develop intiution by studying finite-dimensional models before moving on to abstract situations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00047497
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  • 9
    Electronic Resource
    Electronic Resource
    A first step in modelling plankton growth in the Loosdrecht Lakes (1986)
    Springer
    Aquatic ecology 20 (1986), S. 135-145 
    Details
    ISSN: 1573-5125
    Keywords: eutrophication ; modelling ; carbon cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this paper a dynamic model is presented to simulate plankton growth in the Loosdrecht Lakes. The present, first step version of the model, contains only one algal super-species and incorporates fairly standard formulations for the effects of light irradiance, the extinction coefficient of the water, temperature and the phosphate levels on algal growth. Grazing by zooplankton and detritus dynamics (non-living particulate organic material) are considered essential parts of the carbon cycle. The total phosphorus concentration is used as a timevariable forcing function, which transforms the problem of predicting future water quality levels into the problem of predicting future total phosphorus levels. This requires a separate estimation procedure. However, both types of estimation should be and can be integrated into one single water quality model. The Loosdrecht Lakes seem P-limited in summer. Re-adjustment of certain constants is necessary to simulate Lake Breukeleveen, which differs from the Loosdrecht Lakes in certain characteristics. It is hypothesized that some form of phosphorus cell-quota dynamics may solve this problem. Furthermore, it is discussed as to what extent the hydrological interactions between the Loosdrecht Lakes and Lake Breukeleveen may have caused the differences observed and how this matter could be evaluated through simulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02291158
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  • 10
    Electronic Resource
    Electronic Resource
    Hypothesis formulation and testing in aquatic bioassays: a deterministic model approach (1989)
    Springer
    Hydrobiologia 188-189 (1989), S. 533-542 
    Details
    ISSN: 1573-5117
    Keywords: aquatic toxicity ; bioconcentration ; bioassay ; modelling ; narcotic organics ; chlorobenzenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The paper examines the significance of toxicant kinetics information obtained from aquatic toxicity bioassays and bioconcentration tests. The data, bioconcentration kinetics and acute mortality versus exposure-duration information for juvenile American flagfish (Jordanella foridae) exposed to 1,4-dichlorobenzene, are interpreted in terms of a one-compartment, first-order kinetics model. The output of the model is used to formulate a testable hypothesis regarding the comparison of toxicant kinetics derived from both bioconcentration test exposures and toxicity bioassays. The model's estimates of the toxicant body burden attained at mortality are compared with theoretical and observed body burdens from literature sources. The use of a simple, deterministic residue-based, one-compartment, first-order kinetics model to evaluate existing data, as well as to formulate hypotheses to direct experimental designs, is examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027821
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