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  • 1
    Book
    Book
    Philadelphia, Pa. :Society for Industrial and Applied Mathematics,
    Title: Linear and nonlinear optimization /
    Author: Griva, Igor
    Contributer: Nash , Stephen G. , Sofer, Ariela
    Edition: 2. ed
    Publisher: Philadelphia, Pa. :Society for Industrial and Applied Mathematics,
    Year of publication: 2009
    Pages: XXII, 742 S. : , graph. Darst.
    ISBN: 978-0-89871-661-0
    Type of Medium: Book
    Language: English
    URL: 01  (lizenzfrei)
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  • 2
    Title: ¬A¬ history of scientific computing. Based on papers pres. at the conf. on the history of scientific and numeric computation, Princeton, NJ, 1987
    Contributer: Nash, Stephen G.
    Publisher: Reading, MA u.a. :Addison-Wesley,
    Year of publication: 1990
    Pages: 359 S.
    Type of Medium: Book
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  • 3
    ISSN: 1436-4646
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 45 (1989), S. 529-546 
    ISSN: 1436-4646
    Keywords: Nonlinear optimization ; parallel computing ; block iterative methods ; truncated-Newton methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Truncated-Newton methods are a class of optimization methods suitable for large scale problems. At each iteration, a search direction is obtained by approximately solving the Newton equations using an iterative method. In this way, matrix costs and second-derivative calculations are avoided, hence removing the major drawbacks of Newton's method. In this form, the algorithms are well-suited for vectorization. Further improvements in performance are sought by using block iterative methods for computing the search direction. In particular, conjugate-gradient-type methods are considered. Computational experience on a hypercube computer is reported, indicating that on some problems the improvements in performance can be better than that attributable to parallelism alone.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 152 (1989), S. 141-170 
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Two models for superluminal radio sources predict sharp lower bounds for the apparent velocities of separation. The light echo model predicts a minimum velocityv min=2c, and the dipole field model predictsv min=4.446c. Yahil (1979) has suggested that, if either of these models is correct, thenv min provides a ‘standard velocity’ which can be used to determine the cosmological parametersH andq 0. This is accomplished by estimating a lower envelope for the proper motion vs redshift relation. Yahil also argued that the procedure could easily be generalized to include a nonzero cosmical constant Λ. We derive the formulas relating the proper motion $$\dot \theta$$ to the redshiftz in a Friedmann universe with a nonzero Λ. We show that the determination of a lower envelope for a given sample of measured points $$(z_i ,\dot \theta _i )$$ yields an estimate of the angle of inclinationφ i for each source in the sample. We formulate the estimation of the lower envelope as a constrained maximum likelihood problem with the constraints specified by the expected value of the largest order statistic for the estimatedφ i . We solve this problem numerically using an off-the-shelf nonlinearly constrained nonlinear optimization program from the NAg library. Assuming Λ=0, we apply the estimation procedure to a sample of 27 sources with measured values $$(z_i ,\dot \theta _i )$$ , using both the light echo and the dipole field models. The fits giveH=103 km s−1 Mpc−1 for the light echo model andH=46 km s−1 Mpc−1 for the dipole field model. In both cases the fits giveq 0=0.4, but the uncertainty in this result is too large to rule out the possibility thatq 0〉0.5. When Λ is allowed to be a free parameter, we obtainH=105 km s−1 Mpc−1 for the light echo model andH=47 km s−1 Mpc−1 for the dipole field model. In both cases the fits giveq 0=−1 and Λ/H 0 2 =6.7, but no significance can be attached to these results because of the paucity of measured data at hight redshifts. For all of the fits, we compute the corresponding estimates of theφ i and compare the cumulative distribution of these values with that expected from a sample of randomly oriented sources. In all cases we find a large excess of sources at low-inclination angles (high apparent velocities). The expected selection effect would produce such an excess, but the excess is large enough to suggest a strong contamination of the sample by relativistic beam sources which would only be seen at low inclination angles.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Environmental monitoring and assessment 47 (1997), S. 1-21 
    ISSN: 1573-2959
    Keywords: computer program ; karst-conduit parameters ; quantitative karst-conduit tracing ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Quantitative ground-water tracing of conduit-dominated karst aquifers allows for reliable and practical interpretation of karst ground-water flow. Insights into the hydraulic geometry of the karst aquifer may be acquired that otherwise could not be obtained by such conventional methods as potentiometric-surface mapping and aquifer testing. Contamination of karst aquifers requires that a comprehensive tracer budget be performed so that karst conduit hydraulic-flow and geometric parameters be obtained. Acquisition of these parameters is necessary for estimating contaminant fate-and-transport. A FORTRAN computer program for estimating total tracer recovery from tracer-breakthrough curves is proposed as a standard method. Estimated hydraulic-flow parameters include mean residence time, mean flow velocity, longitudinal dispersivity, Peclet number, Reynolds number, and Froude number. Estimated geometric parameters include karst conduit sinuous distance, conduit volume, cross-sectional area, diameter, and hydraulic depth. These parameters may be used to (1) develop structural models of the aquifer, (2) improve aquifer resource management, (3) improve ground-water monitoring systems design, (4) improve aquifer remediation, and (5) assess contaminant fate-and-transport. A companion paper demonstrates the use of these hydraulic-flow and geometric parameters in a surface-water model for estimating contaminant fate-and-transport in a karst conduit. Two ground-water tracing studies demonstrate the utility of this program for reliable estimation of necessary karst conduit hydraulic-flow and geometric parameters.
    Type of Medium: Electronic Resource
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