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  • Nonlinear algebraic systems  (3)
  • Photosystem II  (3)
  • Springer  (6)
  • Periodicals Archive Online (PAO)
  • 1990-1994  (6)
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  • Springer  (6)
  • Periodicals Archive Online (PAO)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Interval Newton/generalized bisection when there are singularities near roots (1990)
    Springer
    Annals of operations research 25 (1990), S. 181-196 
    Details
    ISSN: 1572-9338
    Keywords: Nonlinear algebraic systems ; Newton's method ; interval arithmetic ; Gauss-Seidel method ; global optimization ; singularities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract Interval Newton methods in conjunction with generalized bisection are important elemetns of algorithms which find theglobal optimum within a specified box X ⊂ ℝn of an objective function ϕ whose critical points are solutions to the system of nonlinear equationsF(X)=0with mathematical certainty, even in finite presision arithmetic. The overall efficiency of such a scheme depends on the power of the interval Newton method to reduce the widths of the coordinate intervals of the box. Thus, though the generalized bisection method will still converge in a box which contains a critical point at which the Jacobian matrix is singular, the process is much more costly in that case. Here, we propose modifications which make the generalized bisection method isolate singular solutions more efficiently. These modifications are based on an observation about the verification property of interval Newton methods and on techniques for detecting the singularity and removing the region containing it. The modifications assume no special structure forF. Additionally, one of the observations should also make the algorithm more efficient when finding nonsingular solutions. We present results of computational experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02283694
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  • 2
    Electronic Resource
    Electronic Resource
    Decomposition of arithmetic expressions to improve the behavior of interval iteration for nonlinear systems (1991)
    Springer
    Computing 47 (1991), S. 169-191 
    Details
    ISSN: 1436-5057
    Keywords: Primary: 65H10 ; secondary: 65G10 ; Nonlinear algebraic systems ; interval arithmetic ; automatic differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Intervalliterationen können in Verbindung mit anderen Verfahren verwendet werden, um alle Lösungen eines nichlinearen Gleichungsystems in einem gegebenen Gebiet mit Sicherheit abzuschätzen, und auch um Approximationen der Lösungen solcher Systeme zu verifizieren. Die Abschätzungen in den Verfahren sind jedoch manchmal nicht hinreichend genau, da Überschätzungen in der Berechnung und in dem Gebrauch der Invervall-Jacobi Matrix auftreten. In der vorliegenden Arbeit werden Intervalliterationen auf einem erweiterten Gleichungssystem behandelt. In diesem System gibt es keine Überschätzungen der Einzelkomponenten der Intervall-Jacobi Matrix, und für die Nichtlinearitären können Abschätzungen angegeben werden. Anhand eines Beispiels wird die Wirkungsweise der behandelten Algorithmen demonstriert.
    Notes: Abstract Interval iteration can be used, in conjunction with other techniques, for rigorously bounding all solutions to a nonlinear system of equations within a given region, or for verifying approximate solutions. However, because of overestimation which occurs when the interval Jacobian matrix is accumulated and applied, straightforward linearization of the original nonlinear system sometimes leads to nonconvergent iteration. In this paper, we examine interval iterations based on an expanded system obtained from the intermediate quantities in the original system. In this system, there is no overestimation in entries of the interval Jacobi matrix, and nonlinearities can be taken into account to obtain sharp bounds. We present an example in detail, algorithms, and detailed experimental results obtained from applying our algorithms to the example.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02253433
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  • 3
    Electronic Resource
    Electronic Resource
    Analysing the responses of photosynthetic CO2 assimilation to long-term elevation of atmospheric CO2 concentration (1993)
    Springer
    Plant ecology 104-105 (1993), S. 33-45 
    Details
    ISSN: 1573-5052
    Keywords: Greenhouse effect ; Chlorophyll fluorescence ; RubisCQ ; Photosystem II ; Stomata ; Quantum efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Understanding how photosynthetic capacity acclimatises when plants are grown in an atmosphere of rising CO2 concentrations will be vital to the development of mechanistic models of the response of plant productivity to global environmental change. A limitation to the study of acclimatisation is the small amount of material that may be destructively harvested from long-term studies of the effects of elevation of CO2 concentration. Technological developments in the measurement of gas exchange, fluorescence and absorption spectroscopy, coupled with theoretical developments in the interpretation of measured values now allow detailed analyses of limitations to photosynthesisin vivo. The use of leaf chambers with Ulbricht integrating spheres allows separation of change in the maximum efficiency of energy transduction in the assimilation of CO2 from changes in tissue absorptance. Analysis of the response of CO2 assimilation to intercellular CO2 concentration allows quantitative determination of the limitation imposed by stomata, carboxylation efficiency, and the rate of regeneration of ribulose 1:5 bisphosphate. Chlorophyll fluorescence provides a rapid method for detecting photoinhibition in heterogeneously illuminated leaves within canopies in the field. Modulated fluorescence and absorption spectroscopy allow parallel measurements of the efficiency of light utilisation in electron transport through photosystems I and IIin situ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048143
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  • 4
    Electronic Resource
    Electronic Resource
    Can CO2 assimilation in maize leaves be predicted accurately from chlorophyll fluorescence analysis? (1993)
    Springer
    Photosynthesis research 37 (1993), S. 89-102 
    Details
    ISSN: 1573-5079
    Keywords: C4 photosynthesis ; chlorophyll fluorescence ; CO2 assimilation ; maize ; Photosystem II ; quantum yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Analysis is made of the energetics of CO2 fixation, the photochemical quantum requirement per CO2 fixed, and sinks for utilising reductive power in the C4 plant maize. CO2 assimilation is the primary sink for energy derived from photochemistry, whereas photorespiration and nitrogen assimilation are relatively small sinks, particularly in developed leaves. Measurement of O2 exchange by mass spectrometry and CO2 exchange by infrared gas analysis under varying levels of CO2 indicate that there is a very close relationship between the true rate of O2 evolution from PS II and the net rate of CO2 fixation. Consideration is given to measurements of the quantum yields of PS II (φ PS II) from fluorescence analysis and of CO2 assimilation ( $$\phi _{CO_2 } $$ ) in maize over a wide range of conditions. The $${{\phi _{PSII} } \mathord{\left/ {\vphantom {{\phi _{PSII} } {\phi _{CO_2 } }}} \right. \kern-\nulldelimiterspace} {\phi _{CO_2 } }}$$ ratio was found to remain reasonably constant (ca. 12) over a range of physiological conditions in developed leaves, with varying temperature, CO2 concentrations, light intensities (from 5% to 100% of full sunlight), and following photoinhibition under high light and low temperature. A simple model for predicting CO2 assimilation from fluorescence parameters is presented and evaluated. It is concluded that under a wide range of conditions fluorescence parameters can be used to predict accurately and rapidly CO2 assimilation rates in maize.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02187468
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  • 5
    Electronic Resource
    Electronic Resource
    Evaluation of the role of State transitions in determining the efficiency of light utilisation for CO2 assimilation in leaves (1993)
    Springer
    Photosynthesis research 38 (1993), S. 15-26 
    Details
    ISSN: 1573-5079
    Keywords: CO2 assimilation ; light harvesting chlorophyll a/b protein complex ; Photosystem I ; Photosystem II ; protein phosphorylation ; quantum yield ; State transition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wheat leaves were exposed to light treatments that excite preferentially Photosystem I (PS I) or Photosystem II (PS II) and induce State 1 or State 2, respectively. Simultaneous measurements of CO2 assimilation, chlorophyll fluorescence and absorbance at 820 nm were used to estimate the quantum efficiencies of CO2 assimilation and PS II and PS I photochemistry during State transitions. State transitions were found to be associated with changes in the efficiency with which an absorbed photon is transferred to an open PS II reaction centre, but did not correlate with changes in the quantum efficiencies of PS II photochemistry or CO2 assimilation. Studies of the phosphorylation status of the light harvesting chlorophyll protein complex associated with PS II (LHC II) in wheat leaves and using chlorina mutants of barley which are deficient in this complex demonstrate that the changes in the effective antennae size of Photosystem II occurring during State transitions require LHC II and correlate with the phosphorylation status of LHC II. However, such correlations were not found in maize leaves. It is concluded that State transitions in C3 leaves are associated with phosphorylation-induced modifications of the PS II antennae, but these changes do not serve to optimise the use of light absorbed by the leaf for CO2 assimilation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00015057
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  • 6
    Electronic Resource
    Electronic Resource
    An interval branch and bound algorithm for bound constrained optimization problems (1992)
    Springer
    Journal of global optimization 2 (1992), S. 259-280 
    Details
    ISSN: 1573-2916
    Keywords: Primary: 65K10 ; Secondary: 65G10 ; Nonlinear algebraic systems ; Newton's method ; interval arithmetic ; Gauss-Seidel method ; global optimization ; singularities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In this paper, we propose modifications to a prototypical branch and bound algorithm for nonlinear optimization so that the algorithm efficiently handles constrained problems with constant bound constraints. The modifications involve treating subregions of the boundary identically to interior regions during the branch and bound process, but using reduced gradients for the interval Newton method. The modifications also involve preconditioners for the interval Gauss-Seidel method which are optimal in the sense that their application selectively gives a coordinate bound of minimum width, a coordinate bound whose left endpoint is as large as possible, or a coordinate bound whose right endpoint is as small as possible. We give experimental results on a selection of problems with different properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00171829
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