ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles  (8,490)
  • Springer  (8,490)
  • National Academy of Sciences
  • 1995-1999  (8,490)
  • 1975-1979
  • 1995  (8,490)
  • Geosciences  (5,315)
  • Computer Science  (2,834)
  • Architecture, Civil Engineering, Surveying  (758)
Collection
  • Articles  (8,490)
Years
  • 1995-1999  (8,490)
  • 1975-1979
Year
Journal
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 3-4 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 1-2 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 11-12 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 7-8 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 5-6 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 9-10 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 81-81 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 86-87 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 90-90 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 91-93 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 94-95 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 88-89 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 108-112 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 99-107 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 96-98 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 129-138 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 121-128 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: In the previous article we covered what asset location systems (ALS) are and the features and benefits they offer. In this article we explore the various features to be considered when acquiring an ALS and steps to be taken. We discuss what users are saying they want in an ALS, including the results of a survey of vehicle tracking system users and providers.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 139-142 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 113-120 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Abstract The vertical component obtained from the Global Positioning System (GPS) observations is from the ellipsoid (a mathematical surface), and therefore needs to be converted to the orthometric height, which is from the geoid (represented by the mean sea level). The common practice is to use existing bench marks (around the four corners of a project area and interpolate for the rest of the area), but in many areas bench marks may not be available, in which case an existing geoid undulation is used. Present available global geoid undulation values are not generally as detailed as needed, and in many areas they are not known better than ±1 to ±5 m, because of many limitations. This article explains the difficulties encountered in obtaining precise geoid undulation with some example computations, and proposes a technique of applying corrections to the best available global geoid undulations using detailed free-air gravity anomalies (within a 2° × 2° area) to get relative centimeter accuracy. Several test computations have been performed to decide the optimal block sizes and the effective spherical distances to compute the regional and the local effects of gravity anomalies on geoid undulations by using the Stokes integral. In one test computation a 2° × 2° area was subdivided into smaller surface elements. A difference of 37.34 ± 1.6 cm in geoid undulation was obtained over the same 2° × 2° area when 1° × 1° block sizes were replaced by a combination of 5' × 5' and 1' × 1' subdivision integration elements (block sizes).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 143-144 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 145-146 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 148-149 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 146-146 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 23-27 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: This is the first in a series of three articles authored by John Beukers. In this series, John will lead us through some of today's relevant radionavigation history putting turbulent times into perspective. Picking out what he considers significant in the current debate, he projects the future for satellite and terrestrial radionavigation systems well into the 21st century.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 48-53 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 38-47 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 54-58 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 59-64 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 13-22 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Asset location systems, including vehicle and property tracking systems, are in the verge of exploding onto the scene for widespread business and personal use. This is due in part to decreased costs of GPS equipment, and greater availability of wireless communication systems, but also largely due to public awareness of their capabilities and benefits. Companies, organizations, and individual consumers that earlier could not justify the costs of tracking systems are now seriously considering their implementation. Public awareness of such systems is growing daily. Newspapers regularly have articles covering the latest applications of GPS. En route nagivation for aircraft, assisting blind people to navigate the streets of a city, and tracking skiers on slopes are some of the topics of recent newspapers articles on GPS. This article explores GPS asset location systems, looks at their features and foibles, and considers their cost, utility, ease of use, and drawbacks.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 28-37 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Executive Summary GPS is a scientific method used as an adjunct to geographic information systems (GIS) for determining high-accuracy control points over large areas. Recent improvements in receiver technology, differential surveying, and software have made use of GPS technology more practical for smaller GIS projects. This article compares three different GPSs with occupation times of 2 and 12 min using an existing control network, comparing the location of the points and the distances between points. The control network internal distances vary from 40 to 280 m, and within 2000 m of the nearest second-order National Geodetic Survey (NGS) triangulation station. The partnership of GPS and GIS will lead to higher surveying integrity while improving digital mapping on the ground over small and large areas. It also allows for postsurvey analysis with solutions coming from multiple base stations. Presented here is a case study of how to achieve highly accurate and effective control points using using GPS/GIS, particularly for a small area.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 65-73 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The NAVSTAR Global Positioning System is a space-based, all-weather, worldwide satellite navigation system. GPS uses the constellation of satellites and associated ground equipment to perform the primary missions of highly accurate navigation, time transfer, and nuclear detonation detection. To achieve these missions, GPS has three clearly defined segments – space, user and control (see Figure 1). The control segment, otherwise referred to as the operational control segment (OCS), consists of the personnel and equipment that controls the space segment and interfaces with the user segment. The OCS is made up of the master control station (MCS), the ground antennas (GA), and the monitor stations (MS). The purpose of this article is to describe how the 2nd Space Operations Squadron runs the MCS, the key element of the OCS.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 74-75 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 76-79 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 80-80 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    Electronic Resource
    Electronic Resource
    Springer
    GPS solutions 1 (1995), S. 85-85 
    ISSN: 1521-1886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    Electronic Resource
    Electronic Resource
    Springer
    Stochastic environmental research and risk assessment 9 (1995), S. 33-47 
    ISSN: 1436-3259
    Keywords: Hidden markov models ; maximum likelihood estimation ; EM algorithm ; martingale estimating function ; forward-backward algorithm ; Monte Carlo ; filtering ; Nash cascade model ; rainfall runoff modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Many stochastic process models for environmental data sets assume a process of relatively simple structure which is in some sense partially observed. That is, there is an underlying process (Xn, n ≥ 0) or (Xt, t ≥ 0) for which the parameters are of interest and physically meaningful, and an observable process (Yn, n ≥ 0) or (Yt, t ≥ 0) which depends on the X process but not otherwise on those parameters. Examples are wide ranging: the Y process may be the X process with missing observations; the Y process may be the X process observed with a noise component; the X process might constitute a random environment for the Y process, as with hidden Markov models; the Y process might be a lower dimensional function or reduction of the X process. In principle, maximum likelihood estimation for the X process parameters can be carried out by some form of the EM algorithm applied to the Y process data. In the paper we review some current methods for exact and approximate maximum likelihood estimation. We illustrate some of the issues by considering how to estimate the parameters of a stochastic Nash cascade model for runoff. In the case of k reservoirs, the outputs of these reservoirs form a k dimensional vector Markov process, of which only the kth coordinate process is observed, usually at a discrete sample of time points.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    Electronic Resource
    Electronic Resource
    Springer
    Stochastic environmental research and risk assessment 9 (1995), S. 117-132 
    ISSN: 1436-3259
    Keywords: River Quality ; network ; computer model ; Thermodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract In this paper, concepts of network thermodynamics are applied to a river water quality model, which is based on Streeter-Phelps equations, to identify the corresponding physical components and their topology. Then, the randomness in the parameters, input coefficients and initial conditions are modeled by Gaussian white noises. From the stochastic components of the physical system description of problem and concepts of physical system theory, a set of stochastic differential equations can be automatically generated in a computer and the recent developments on the automatic formulation of the moment equations based on Ito calculus can be used. This procedure is illustrated through the solution of an example of stochastic river water quality problem and it is also shown how other related problems with different configurations can be automatically solved in a computer using just one software.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Electronic Resource
    Electronic Resource
    Springer
    Stochastic environmental research and risk assessment 9 (1995), S. 171-205 
    ISSN: 1436-3259
    Keywords: AR-AIC-Bayes filter ; autoregressive spectral density estimation ; diagnostic checks for ARMA models ; exploratory data analysis ; fast Fourier transform ; Hurst coefficient ; long-memory times series ; periodogram smoothing ; riverflow time series ; spectral density plots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Current methods of estimation of the univariate spectral density are reviewed and some improvements are made. It is suggested that spectral analysis may perhaps be best thought of as another exploratory data analysis (EDA) tool which complements, rather than competes with, the popular ARMA model building approach. A new diagnostic check for ARMA model adequacy based on the nonparametric spectral density is introduced. Additionally, two new algorithms for fast computation of the autoregressive spectral density function are presented. For improving interpretation of results, a new style of plotting the spectral density function is suggested. Exploratory spectral analyses of a number of hydrological time series are performed and some interesting periodicities are suggested for further investigation. The application of spectral analysis to determine the possible existence of long memory in natural time series is discussed with respect to long riverflow, treering and mud varve series. Moreover, a comparison of the estimated spectral densities suggests the ARMA models fitted previously to these datasets adequately describe the low frequency component. Finally, the software and data used in this paper are available by anonymous ftp from fisher.stats.uwo.ca.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    Electronic Resource
    Electronic Resource
    Springer
    Stochastic environmental research and risk assessment 9 (1995), S. 215-237 
    ISSN: 1436-3259
    Keywords: Computation ; discretization ; entropy ; networks ; time averaging ; water quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The computational aspects of using a new, entropy-based, theory to predict water quality values at discontinued water quality monitoring stations are discussed. The main computational issues addressed are the level of discretization used in converting the continuous probability distribution of water quality values to the discrete levels required for the entropy function, and the choice of the interval of time for which to assign the value of the water quality (period of time averaging) through the entropy function. Unlike most cases of entropy applications involving discretization of continuous functions the results of using entropy theory to predict water quality values at discontinued monitoring stations in this application appear to be insensitive to the choice of the level of discretization even down to the very coarse level discretization associated with only eight intervals. However, depending on the length of record available the choice of the time interval for which the water quality values are assigned (period for time averaging) appear to have a significant impact on the accuracy of the results.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    Electronic Resource
    Electronic Resource
    Springer
    Stochastic environmental research and risk assessment 9 (1995), S. 13-32 
    ISSN: 1436-3259
    Keywords: Distributed parameter filter ; shallow water equations ; distributed dynamical systems ; data assimilation ; white Gaussian noise
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Distributed parameter filtering theory is employed for estimating the state variables and associated error covariances of a dynamical distributed system under highly random tidal and meteorological influences. The stochastic-deterministic mathematical model of the physical system under study consists of the shallow water equations described by the momentum and continuity equations in which the external forces such as Coriolis force, wind friction, and atmospheric pressure are considered. White Gaussian noises in the system and measurement equations are used to account for the inherent stochasticity of the system. By using an optimal distributed parameter filter, the information provided by the stochastic dynamical model and the noisy measurements taken from the actual system are combined to obtain an optimal estimate of the state of the system, which in turn is used as the initial condition for the prediction procedure. The approach followed here has numerical approximation carried out at the end, which means that the numerical discretization is performed in the filtering equations, and not in the equations modelling the system. Therefore, the continuous distributed nature of the original system is maintained as long as possible and the propagation of modelling errors in the problem is minimized. The appropriateness of the distributed parameter filter is demonstrated in an application involving the prediction of storm surges in the North Sea. The results confirm excellent filter performance with considerable improvement with respect to the deterministic prediction.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    Electronic Resource
    Electronic Resource
    Springer
    Stochastic environmental research and risk assessment 9 (1995), S. 77-88 
    ISSN: 1436-3259
    Keywords: Extreme rainfalls ; partial duration series ; regional estimation ; Bayes' theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Based on the Partial Duration Series model a regional Bayesian approach is introduced in the modelling of extreme rainfalls from a country-wide system of recording raingauges in Denmark. The application of the Bayesian principles is derived in case of both exponential and generalized Pareto-distributed exceedances. The method is applied to, respectively, the total precipitation depth and the maximum 10 minutes rain intensity of individual storms from 41 stations. By means of the regional analysis prior distributions of the parameters in the Partial Duration Series model are estimated. It is shown that the regional approach significantly reduces the uncertainty of the T-year event estimator compared to estimation based solely on at-site data. In addition, the regional approach provides quantile estimates at non-monitored sites.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 68 (1995), S. 105-130 
    ISSN: 1436-4646
    Keywords: primary 49B34 ; secondary 90C31 ; 93C30 ; Variational inequalities ; Sensitivity analysis ; Generalized Jacobian
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Optimization problems with variational inequality constraints are converted to constrained minimization of a local Lipschitz function. To this minimization a non-differentiable optimization method is used; the required subgradients of the objective are computed by means of a special adjoint equation. Besides tests with some academic examples, the approach is applied to the computation of the Stackelberg—Cournot—Nash equilibria and to the numerical solution of a class of quasi-variational inequalities.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 69 (1995), S. 1-43 
    ISSN: 1436-4646
    Keywords: Mathematical programming ; Cutting planes ; Analytic center
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Anoracle for a convex setS ⊂ ℝ n accepts as input any pointz in ℝ n , and ifz ∈S, then it returns ‘yes’, while ifz ∉S, then it returns ‘no’ along with a separating hyperplane. We give a new algorithm that finds a feasible point inS in cases where an oracle is available. Our algorithm uses the analytic center of a polytope as test point, and successively modifies the polytope with the separating hyperplanes returned by the oracle. The key to establishing convergence is that hyperplanes judged to be ‘unimportant’ are pruned from the polytope. If a ball of radius 2−L is contained inS, andS is contained in a cube of side 2 L+1, then we can show our algorithm converges after O(nL 2) iterations and performs a total of O(n 4 L 3+TnL 2) arithmetic operations, whereT is the number of arithmetic operations required for a call to the oracle. The bound is independent of the number of hyperplanes generated in the algorithm. An important application in which an oracle is available is minimizing a convex function overS.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 69 (1995), S. 45-73 
    ISSN: 1436-4646
    Keywords: Cutting plane ; Stochastic programming ; Analytic center ; Interior-point method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract The stochastic linear programming problem with recourse has a dual block-angular structure. It can thus be handled by Benders' decomposition or by Kelley's method of cutting planes; equivalently the dual problem has a primal block-angular structure and can be handled by Dantzig-Wolfe decomposition—the two approaches are in fact identical by duality. Here we shall investigate the use of the method of cutting planes from analytic centers applied to similar formulations. The only significant difference form the aforementioned methods is that new cutting planes (or columns, by duality) will be generated not from the optimum of the linear programming relaxation, but from the analytic center of the set of localization.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 69 (1995), S. 237-253 
    ISSN: 1436-4646
    Keywords: Variational inequality ; Nonlinear complementarity ; Nonlinear programming ; Continuation method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract This paper presents a continuation method for monotone variational inequality problems based on a new smooth equation formulation. The existence, uniqueness and limiting behavior of the path generated by the method are analyzed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 69 (1995), S. 269-309 
    ISSN: 1436-4646
    Keywords: Quadratic programming ; Submodular constraints ; Kuhn-Tucker conditions ; Lexicographically optimal flow ; Parametric maximum flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We present new strongly polynomial algorithms for special cases of convex separable quadratic minimization over submodular constraints. The main results are: an O(NM log(N 2/M)) algorithm for the problemNetwork defined on a network onM arcs andN nodes; an O(n logn) algorithm for thetree problem onn variables; an O(n logn) algorithm for theNested problem, and a linear time algorithm for theGeneralized Upper Bound problem. These algorithms are the best known so far for these problems. The status of the general problem and open questions are presented as well.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 69 (1995), S. 335-349 
    ISSN: 1436-4646
    Keywords: Polyhedral combinatorics ; Valid inequalities ; Travelling salesman ; Worst-case analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We consider most of the known classes of valid inequalities for the graphical travelling salesman polyhedron and compute the worst-case improvement resulting from their addition to the subtour polyhedron. For example, we show that the comb inequalities cannot improve the subtour bound by a factor greater than 10/9. The corresponding factor for the class of clique tree inequalities is 8/7, while it is 4/3 for the path configuration inequalities.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 70 (1995), S. 1-16 
    ISSN: 1436-4646
    Keywords: Stochastic programming ; Polyhedral functions ; Simplicial functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract A dual method is presented to solve a linearly constrained optimization problem with convex, polyhedral objective function, along with a fast bounding technique, for the optimum value. The method can be used to solve problems, obtained from LPs, where some of the constraints are not required to be exactly satisfied but are penalized by piecewise linear functions, which are added to the objective function of the original problem. The method generalizes an earlier solution technique developed by Prékopa (1990). Applications to stochastic programming are also presented.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 70 (1995), S. 107-122 
    ISSN: 1436-4646
    Keywords: Linear complementarity problem ; Predictor—corrector algorithm ; Complexity analysis ; Central trajectory ; Curvature integral ; Interior-point methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract In this paper, we propose a predictor—corrector-type algorithm for solving the linear complementarity problem (LCP), and prove that the actual number of iterations needed by the algorithm is bounded from above and from below by a curvature integral along the central trajectory of the problem. This curvature integral is not greater than, and possibly smaller than, the best upper bound obtained in the literature to date.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 70 (1995), S. 159-172 
    ISSN: 1436-4646
    Keywords: Parametric nonlinear programming ; Directional differentiability ; B-derivative ; Piecewise smooth function ; Nonunique multipliers ; Degeneracy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Consider a parametric nonlinear optimization problem subject to equality and inequality constraints. Conditions under which a locally optimal solution exists and depends in a continuous way on the parameter are well known. We show, under the additional assumption of constant rank of the active constraint gradients, that the optimal solution is actually piecewise smooth, hence B-differentiable. We show, for the first time to our knowledge, a practical application of quadratic programming to calculate the directional derivative in the case when the optimal multipliers are not unique.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 70 (1995), S. 191-200 
    ISSN: 1436-4646
    Keywords: Strictly pseudomonotone map ; Z-map ; Complementarity problem ; Least element problem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Strictly pseudomonotoneZ-maps operating on Banach lattices are considered. Equivalence of complementarity problems and least-element problems is established under certain regularity and growth conditions. This extends a recent result by Riddell (1981) for strictly monotoneZ-maps to the pseudomonotone case. Some other problems equivalent to the above are discussed as well.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 70 (1995), S. 251-277 
    ISSN: 1436-4646
    Keywords: Linear programming ; Barrier methods ; Interior-point methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Many interior-point methods for linear programming are based on the properties of the logarithmic barrier function. After a preliminary discussion of the convergence of the (primal) projected Newton barrier method, three types of barrier method are analyzed. These methods may be categorized as primal, dual and primal—dual, and may be derived from the application of Newton's method to different variants of the same system of nonlinear equations. A fourth variant of the same equations leads to a new primal—dual method. In each of the methods discussed, convergence is demonstrated without the need for a nondegeneracy assumption or a transformation that makes the provision of a feasible point trivial. In particular, convergence is established for a primal—dual algorithm that allows a different step in the primal and dual variables and does not require primal and dual feasibility. Finally, a new method for treating free variables is proposed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    ISSN: 1436-4646
    Keywords: Linear programming ; Mixed-integer programming ; Large-scale optimization ; Airline fleet assignment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Given a flight schedule and set of aircraft, the fleet assignment problem is to determine which type of aircraft should fly each flight segment. This paper describes a basic daily, domestic fleet assignment problem and then presents chronologically the steps taken to solve it efficiently. Our model of the fleet assignment problem is a large multi-commodity flow problem with side constraints defined on a time-expanded network. These problems are often severely degenerate, which leads to poor performance of standard linear programming techniques. Also, the large number of integer variables can make finding optimal integer solutions difficult and time-consuming. The methods used to attack this problem include an interior-point algorithm, dual steepest edge simplex, cost perturbation, model aggregation, branching on set-partitioning constraints and prioritizing the order of branching. The computational results show that the algorithm finds solutions with a maximum optimality gap of 0.02% and is more than two orders of magnitude faster than using default options of a standard LP-based branch-and-bound code.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 71 (1995), S. 77-100 
    ISSN: 1436-4646
    Keywords: Convex linearly constrained problems ; Variational inequalities ; Interior methods ; Entropy-like proximal method ; Maximal monotone operator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract In this paper, an entropy-like proximal method for the minimization of a convex function subject to positivity constraints is extended to an interior algorithm in two directions. First, to general linearly constrained convex minimization problems and second, to variational inequalities on polyhedra. For linear programming, numerical results are presented and quadratic convergence is established.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 71 (1995), S. 29-50 
    ISSN: 1436-4646
    Keywords: Max-cut ; Cut polytope ; Metric polytope ; Linear relaxation ; One-third-integrality ; Box one-third-integrality ; Forbidden minor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Given a graphG = (V, E), the metric polytopeS (G) is defined by the inequalitiesx(F) − x(C∖F) ⩽ |F| − 1 for $$F \subseteq C$$ , |F| odd,C cycle ofG, and 0 ⩽x e ⩽ 1 fore ∈ E. Optimization overS (G) provides an approximation for the max-cut problem. The graphG is called 1/d-integral if all the vertices ofS(G) have their coordinates in{i/d ∣ 0 ⩽ i ⩽ d}. We prove that the class of 1/d-integral graphs is closed under minors, and we present several minimal forbidden minors for 1/3-integrality. In particular, we characterize the 1/3-integral graphs on seven nodes. We study several operations preserving 1/d-integrality, in particular, thek-sum operation for 0 ⩽k ⩽ 3. We prove that series parallel graphs are characterized by the following stronger property. All vertices of the polytopeS (G) ∩ {x ∣ ℓ ⩽ x ⩽ u} are 1/3-integral for every choice of 1/3-integral boundsℓ, u on the edges ofG.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 71 (1995), S. 101-112 
    ISSN: 1436-4646
    Keywords: Minmax ; Maximal covering problems ; Multi criteria decision-making
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract In this paper we introduce the parametric minquantile problem, a weighted generalisation ofkth maximum minimisation. It is shown that, under suitable quasiconvexity assumptions, its resolution can be reduced to solving a polynomial number of minmax problems. It is also shown how this simultaneously solves (parametric) maximal covering problems. It follows that bicriteria problems, where the aim is to both maximize the covering and minimize the cover-level, are reducible to a discrete problem, on which any multiple criteria method may be applied.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 71 (1995), S. 71-76 
    ISSN: 1436-4646
    Keywords: Location theory ; Fermat—Weber problem ; Weiszfeld's iterative algorithm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract The Fermat—Weber location problem requires finding a point in ℝ N that minimizes the sum of weighted Euclidean distances tom given points. A one-point iterative method was first introduced by Weiszfeld in 1937 to solve this problem. Since then several research articles have been published on the method and generalizations thereof. Global convergence of Weiszfeld's algorithm was proven in a seminal paper by Kuhn in 1973. However, since them given points are singular points of the iteration functions, convergence is conditional on none of the iterates coinciding with one of the given points. In addressing this problem, Kuhn concluded that whenever them given points are not collinear, Weiszfeld's algorithm will converge to the unique optimal solution except for a denumerable set of starting points. As late as 1989, Chandrasekaran and Tamir demonstrated with counter-examples that convergence may not occur for continuous sets of starting points when the given points are contained in an affine subspace of ℝ N . We resolve this open question by proving that Weiszfeld's algorithm converges to the unique optimal solution for all but a denumerable set of starting points if, and only if, the convex hull of the given points is of dimensionN.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 71 (1995), S. 153-177 
    ISSN: 1436-4646
    Keywords: Network optimization ; Assignment problem ; Algorithms ; Experimental evaluation ; Cost scaling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract The cost scaling push-relabel method has been shown to be efficient for solving minimum-cost flow problems. In this paper we apply the method to the assignment problem and investigate implementations of the method that take advantage of assignment's special structure. The results show that the method is very promising for practical use.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 71 (1995), S. 195-206 
    ISSN: 1436-4646
    Keywords: Superfluous matrix ; Linear complementarity problem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Superfluous matrices were introduced by Howe (1983) in linear complementarity. In general, producing examples of this class is tedious (a few examples can be found in Chapter 6 of Cottle, Pang and Stone (1992)). To overcome this problem, we define a new class of matrices $$\bar Z$$ and establish that in $$\bar Z$$ superfluous matrices of any ordern ⩾ 4 can easily be constructed. For every integerk, an example of a superfluous matrix of degreek is exhibited in the end.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 71 (1995), S. 249-258 
    ISSN: 1436-4646
    Keywords: Combinatorial optimization ; Integrality of polyhedra ; Generalized set packing ; Covering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract A 0, ±1-matrixA is balanced if, in every submatrix with two nonzero entries per row and column, the sum of the entries is a multiple of four. This definition was introduced by Truemper (1978) and generalizes the notion of a balanced 0, 1-matrix introduced by Berge (1970). In this paper, we extend a bicoloring theorem of Berge (1970) and total dual integrality results of Fulkerson, Hoffman and Oppenheim (1974) to balanced 0, ±1-matrices.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 71 (1995), S. 369-370 
    ISSN: 1436-4646
    Keywords: Local Lipschitz property ; Infinite-dimensional Hilbert space
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract An oversight in a paper of Correa and Lemaréchal (this journal, 1993) is noted; a counterexample is given.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 70 (1995), S. 27-45 
    ISSN: 1436-4646
    Keywords: Convex polytopes ; Enumeration of faces ; Adjacency ; Segments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We introduce the concept of a segment of a degenerate convex polytope specified by a system of linear constraints, and explain its importance in developing algorithms for enumerating the faces. Using segments, we describe an algorithm that enumerates all the faces, in time polynomial in their number. The role of segments in the unsolved problem of enumerating the extreme points of a convex polytope specified by a degenerate system of linear constraints, in time polynomial in the number of extreme points, is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 70 (1995), S. 47-72 
    ISSN: 1436-4646
    Keywords: Bilevel programming ; Nonlinear nonconvex ; Nondifferentiable optimization ; Economic planning ; Sensitivity analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract This paper is concerned with general nonlinear nonconvex bilevel programming problems (BLPP). We derive necessary and sufficient conditions at a local solution and investigate the stability and sensitivity analysis at a local solution in the BLPP. We then explore an approach in which a bundle method is used in the upper-level problem with subgradient information from the lower-level problem. Two algorithms are proposed to solve the general nonlinear BLPP and are shown to converge to regular points of the BLPP under appropriate conditions. The theoretical analysis conducted in this paper seems to indicate that a sensitivity-based approach is rather promising for solving general nonlinear BLPP.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 70 (1995), S. 123-148 
    ISSN: 1436-4646
    Keywords: Generalized equations ; Variational inequalities ; Nonlinear programming ; Sensitivity analysis ; Power series ; Strong regularity ; Constrained optimization ; Perturbation theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We show that the solution of a strongly regular generalized equation subject to a scalar perturbation expands in pseudopower series in terms of the perturbation parameter, i.e., the expansion of orderk is the solution of generalized equations expanded to orderk and thus depends itself on the perturbation parameter. In the polyhedral case, this expansion reduces to a usual Taylor expansion. These results are applied to the problem of regular perturbation in constrained optimization. We show that, if the strong regularity condition is satisfied, the property of quadratic growth holds and, at least locally, the solutions of the optimization problem and of the associated optimality system coincide. If, in addition the number of inequality constraints is finite, the solution and the Lagrange multiplier can be expanded in Taylor series. If the data are analytic, the solution and the multiplier are analytic functions of the perturbation parameter.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 70 (1995), S. 201-209 
    ISSN: 1436-4646
    Keywords: Disjoint paths ; Joins ; Packing cuts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Seymour (1981) proved that the cut criterion is necessary and sufficient for the solvability of the edge-disjoint paths problem when the union of the supply graph and the demand graph is planar and Eulerian. When only planarity is required, Middendorf and Pfeiffer (1993) proved the problem to be NP-complete. For this case, Korach and Penn (1992) proved that the cut criterion is sufficient for the existence of a near-complete packing of paths. Here we generalize this result by showing how a natural strengthening of the cut criterion yields better packings of paths. Analogously to Seymour's approach, we actually prove a theorem on packing cuts in an arbitrary graph and then the planar edge-disjoint paths case is obtained by planar dualization. The main result is derived from a theorem of Sebő (1990) on the structure of ±1 weightings of a bipartite graph with no negative circuits.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 70 (1995), S. 279-351 
    ISSN: 1436-4646
    Keywords: Linear programming ; Complexity theory ; Interior-point methods ; Semi-definite programming ; Condition numbers ; Convex programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We propose analyzing interior-point methods using notions of problem-instance size which are direct generalizations of the condition number of a matrix. The notions pertain to linear programming quite generally; the underlying vector spaces are not required to be finite-dimensional and, more importantly, the cones defining nonnegativity are not required to be polyhedral. Thus, for example, the notions are appropriate in the context of semi-definite programming. We prove various theorems to demonstrate how the notions can be used in analyzing interior-point methods. These theorems assume little more than that the interiors of the cones (defining nonnegativity) are the domains of self-concordant barrier functions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 67
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 71 (1995), S. 17-28 
    ISSN: 1436-4646
    Keywords: Descent method ; Proximal algorithm ; Direction-finding subproblem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Most of the descent methods developed so far suffer from the computational burden due to a sequence of constrained quadratic subproblems which are needed to obtain a descent direction. In this paper we present a class of proximal-type descent methods with a new direction-finding subproblem. Especially, two of them have a linear programming subproblem instead of a quadratic subproblem. Computational experience of these two methods has been performed on two well-known test problems. The results show that these methods are another very promising approach for nondifferentiable convex optimization.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 68
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 71 (1995), S. 51-69 
    ISSN: 1436-4646
    Keywords: Smoothing ; Convex inequalities ; Linear complementarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract A smooth approximationp (x, α) to the plus function max{x, 0} is obtained by integrating the sigmoid function 1/(1 + e−αx ), commonly used in neural networks. By means of this approximation, linear and convex inequalities are converted into smooth, convex unconstrained minimization problems, the solution of which approximates the solution of the original problem to a high degree of accuracy forα sufficiently large. In the special case when a Slater constraint qualification is satisfied, an exact solution can be obtained for finiteα. Speedup over MINOS 5.4 was as high as 1142 times for linear inequalities of size 2000 × 1000, and 580 times for convex inequalities with 400 variables. Linear complementarity problems are converted into a system of smooth nonlinear equations and are solved by a quadratically convergent Newton method. For monotone LCPs with as many as 10 000 variables, the proposed approach was as much as 63 times faster than Lemke's method.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 69
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 71 (1995), S. 127-136 
    ISSN: 1436-4646
    Keywords: Parametric optimization ; Mixed-integer program ; Value functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We identify a class of formulas computable in polynomial time such that the functions defined by these formulas are precisely the value functions of mixed-integer programs with rational constraint coefficients.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 70
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 71 (1995), S. 137-151 
    ISSN: 1436-4646
    Keywords: Quadratic assignment problem ; Lower bounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We consider transformations of the (metric) Quadratic Assignment Problem (QAP) that exploit the metric structure of a given instance. We show in particular how the structural properties of rectangular grids can be used to improve a given lower bound. Our work is motivated by previous research of Palubetskes (1988), and it extends a bounding approach proposed by Chakrapani and Skorin-Kapov (1993). Our computational results indicate that the present approach is practical; it has been applied to problems of dimension up ton = 150. Moreover, the new approach yields by far the best lower bounds on most of the instances of metric QAPs that we considered.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 71
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 71 (1995), S. 207-219 
    ISSN: 1436-4646
    Keywords: Subgradient optimization ; Relaxation methods ; Projection methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We study conditions for convergence of a generalized subgradient algorithm in which a relaxation step is taken in a direction, which is a convex combination of possibly all previously generated subgradients. A simple condition for convergence is given and conditions that guarantee a linear convergence rate are also presented. We show that choosing the steplength parameter and convex combination of subgradients in a certain sense optimally is equivalent to solving a minimum norm quadratic programming problem. It is also shown that if the direction is restricted to be a convex combination of the current subgradient and the previous direction, then an optimal choice of stepsize and direction is equivalent to the Camerini—Fratta—Maffioli modification of the subgradient method.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 72
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 71 (1995), S. 221-245 
    ISSN: 1436-4646
    Keywords: Linear programming ; Presolving ; Interior-point methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Most modern linear programming solvers analyze the LP problem before submitting it to optimization. Some examples are the solvers WHIZARD (Tomlin and Welch, 1983), OB1 (Lustig et al., 1994), OSL (Forrest and Tomlin, 1992), Sciconic (1990) and CPLEX (Bixby, 1994). The purpose of the presolve phase is to reduce the problem size and to discover whether the problem is unbounded or infeasible. In this paper we present a comprehensive survey of presolve methods. Moreover, we discuss the restoration procedure in detail, i.e., the procedure that undoes the presolve. Computational results on the NETLIB problems (Gay, 1985) are reported to illustrate the efficiency of the presolve methods.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 73
    Electronic Resource
    Electronic Resource
    Springer
    Computing 54 (1995), S. 303-316 
    ISSN: 1436-5057
    Keywords: 05 C 60 ; 05 C 85 ; Graph isomorphism ; automorphism partition ; polynomial algorithm ; chordal graphs ; graphs with fewP 4s
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Ein Graph ist chordal, wenn er keine sehnenlosen Kreise der Länge mindestens vier enthält und (q, t), wenn keine Menge von höchstensq Knoten mehr alst Wege der Länge drei induziert. Es ist bekannt, daß das Isomorphieproblem für chordale Graphen und für (6, 3) Graphen Isomorphie-vollständig ist. Wir stellen polynomiale Verfahren vor zur Bestimmung der Automorphiepartition und zum Testen der Isomorphie von Graphen, die sowohl chrodal als auch (6, 3) sind. Der zugang basiert auf dem Studium von simplizialen Partitionen von chordalen Graphen. Es wird gezeigt, daß für chordale (6, 3) Graphen die Automorphiepartition mit der gröbsten regulären simplizialen Partition übereinstimmt. Dies führt zu einemO(n+m logn) isomorphietest.
    Notes: Abstract A graph is chordal if it contains no chordless cycles of length at least four and (q, t) if no set of at mostq vertices induces more thant paths of length three. It is known that the isomorphism problem is isomorphism complete for chordal graphs and for (6, 3) graphs. We present polynomial methods to determine the automorphism partition and to test isomorphism of graphs which are both chordal and (6, 3). The approach is based on the study of simplicial partitions of chordal graphs. It is proved that for chordal (6, 3) graphs the automorphism partition coincides with the coarsest regular simplicial partition. This yields anO(n+m logn) isomorphism test.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 74
    Electronic Resource
    Electronic Resource
    Springer
    Computing 54 (1995), S. 317-330 
    ISSN: 1436-5057
    Keywords: 65M06 ; 65M55 ; 65Y05 ; Parabolic partial differential equation ; Multigird ; parallel computing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Die Erscheinung von Parallelrechnern hat zur Entwicklung neuer Lösungsverfahren for zeitabhängige partielle Differentialgleichungen geführt. Zwei der in letzter Zeit entwickelten Verfahren — die Mehrgitter-Wellenformrelaxations-Methode und die zeitparallele Mehrgittermethode —haben zum Ziel, die Lösung zu vielen verschiedenen diskreten Zeitpunkten simultan zu berechnen. In dieser Arbeit wird anhand der Ergebnisse einer Fourier-Analyse für ein Modell-problem das Konvergenzverhalten beider Methoden verglichen.
    Notes: Abstract The advent of parallel computers has led to the development of new solution algorithms for time-dependent partial differential equations. Two recently developed methods, multigrid waveform relaxation and time-parallel multigrid, have been designed to solve parabolic partial differential equations on many time-levels simultaneously. This paper compares the convergence properties of these methods, based on the results of an exponential Fourier mode analysis for a model problem.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 75
    Electronic Resource
    Electronic Resource
    Springer
    Computing 54 (1995), S. 251-272 
    ISSN: 1436-5057
    Keywords: Iterative process ; variational inequality ; non-accurate iteration ; projection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Diese Arbeit behandelt numerische Methoden zur Lösung linearer Variations-Ungleichungen auf einer abgeschlossenen konvexen Teilmenge des ℝn. Es gibt zwar zahlreiche Iterationsverfahren für den FallC=ℝ + n für den Fall einer beliebigen abgeschlossenen konvexen TeilmengeC wurde aber nur wenig vorgeschlagen. Die wesentliche Schwierigkeit in diesem Fall liegt in den Nichtlinearitäten des Randes vonC. In dieser Arbeit werden Iterationsverfahren zur Lösung linearer Variations-Ungleichungen auf einer beliebigen abgeschlossenen konvexen TeilmengeC entwickelt. In unseren Algorithmen wird die Berechnung einer linearen Variations-Ungleichung zerlegt in eine Folge von Projektionen eines Vektors auf die abgeschlossene konvexe TeilmengeC, die berechnet werden können, solange die Bestimmungsgleichungen des Randes gegeben sind. Insbesondere kann mit unseren Iterationsverfahren leicht eine Lösung berechnet werden fürC als Würfel, Kugel, Ellipsoid etc. Außerdem werden Näherungs-Iterationen, Abschätzung der Lösungen für unbeschränkte Bereiche und die Theorie der Randapproximation untersucht. Weiters wird eine notwendige und hinreichende Bedingung dafür angegeben, daß ein Vektor eine Näherungslösung ist. Schließlich werden einige numerische Beispiele präsentiert, die zeigen, daß die vorgestellten Algorithmen effektiv und effizient sind.
    Notes: Abstract This paper deals with numerical methods for solving linear variational inequalities on an arbitrary closed convex subsetC of ℝ n . Although there were numerous iterations studied for the caseC=ℝ + n , few were proposed for the case whenC is a closed convex subset. The essential difficulty in this case is the nonlinearities ofC's boundaries. In this paper iteration processes are designed for solving linear variational inequalities on an arbitrary closed convex subsetC. In our algorithms the computation of a linear variational inequality is decomposed into a sequence of problems of projecting a vector to the closed convex subsetC, which are computable as long as the equations describing the boundaries are given. In particular, using our iterations one can easily compute a solution whenC is one of the common closed convex subsets such as cube, ball, ellipsoid, etc. The non-accurate iteration, the estimate of the solutions on unbounded domains and the theory of approximating the boundaries are also established. Moreover, a necessary and sufficient condition is given for a vector to be an approximate solution. Finally, some numerical examples are presented, which show that the designed algorithms are effective and efficient. The exposition of this paper is self-contained.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 76
    Electronic Resource
    Electronic Resource
    Springer
    Computing 54 (1995), S. 331-346 
    ISSN: 1436-5057
    Keywords: 65N55 ; 65N30 ; Frequency decomposition ; multi-level method ; finite elements ; hierarchical basis ; additive and multiplicative Schwarz methods ; subspace decomposition ; robustness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Kürzlich haben wir eine effektive Modifizierung des Frequenzzerlegungs-Mehrgitterverfahrens vorgestellt. In diesem Artikel wird die multiplikative Variante dieses Verfahrens untersucht. Unter Verwendung der Theorie der Unterraumkorrekturverfahren wird die Robustheit sowohl für die multiplikative als auch für die additive Variante bei Anwendung auf anisotrope Probleme mit beliebiger Raumdimension bewiesen. Die Implementierung beider Varianten wird diskutiert und numerische Ergebnisse werden angegeben.
    Notes: Abstract Recently, we introduced a cheap modification of Hackbusch'sFrequency Decomposition multi-level method. In this paper, the multiplicative variant of this method is studied. Using the theory of Subspace Correction Methods robustness is proved of both the multiplicative and additive variant applied to anisotropic problems in an arbitrary number of space dimensions. Implementation of both variants is discussed and numerical results are given.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 77
    Electronic Resource
    Electronic Resource
    Springer
    Computing 54 (1995), S. 347-357 
    ISSN: 1436-5057
    Keywords: 65G10 ; 65L05 ; 65L07 ; Interval arithmetic ; interval methods for the initial value problem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wenn Systeme gewöhnlicher Differentialgleichungen mit Intervallmethoden gelöst werden, besteht die Hauptschwierigkeit in der Reduktion des Wrappingeffekts. Die verschiedenen bis jetzt vorgeschlagenen Lösungen sind nur bei engen Anfangsintervallen oder speziellen Gleichungsklassen anwendbar. Diese Arbeit beschreibt einen Algorithmus, der statt Intervallen eine größere Familie von Mengen verwendet. Der Algorithmus führt zu einem sehr geringen Wrappingeffekt und ist bei beliebigem Gleichungstyp und weiten Anfangsintervallen anwendbar. Zum gegenwärtigen Zeitpunkt können nur 2-dimensionale Probleme behandelt werden.
    Notes: Abstract When solving ODEs by interval methods, the main difficulty is reducing the wrapping effect. Various solutions have been put forward, all of which are applicable for narrow initial intervals or to particular classes of equations only. This paper describes an algorithm which, instead of intervals, uses a larger family of sets. The algorithm exhibits a very small wrapping effect and applies to any type of equation and initial region. For the time being it handles only two-dimensional equations.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 78
    Electronic Resource
    Electronic Resource
    Springer
    Computing 54 (1995), S. 359-375 
    ISSN: 1436-5057
    Keywords: AMS(MOS) ; 65H05 ; Polynomial zeros ; Eulidean division of Chebyshev expansions ; Sturm sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir stellen einen global konvergenten Algorithmus zur Berechnung aller Nullstellen eines Polynomsp n ,p n (z) = ∑ v = 0 n a v z v, mit reellen Koeffizienten vor. Durch Aufspalten vonp n (exp(it)) in seinen Real-und Imaginärteil können wir mittels Euklidischer Division von Čebyševentwicklungen und durch Argumentation mit Sturmschen Ketten entscheiden, obp n Nullstellen im Einheitskreis hat und wie viele Nullstellen auf dem Rand und im Inneren davon liegen. Somit erhalten wir mittels einer Bisektionsstrategie die Beträge aller Nullstellen bis auf eine vorgegebene Genauigkeit, und zusätzlich finden wir die Argumente als reelle Nullstellen eines Polynoms niedrigen Grades. Auf diese Weise erzeugen wir Startnäherungen für alle Nullstellen, die in einem letzten Schritt mittels eines iterativen Prozesses höherer Konvergenzordnung verbessert werden (z.B. Newton- oder Bairstowverfahren).
    Notes: Abstract We present a globally convergent algorithm for calculating all zeros of a polynomialp n ,p n (z) = ∑ v = 0 n a v z v, with real coefficients. Splittingp n (exp(it)) into its real and imaginary part we can decide via Euclidean division of Chebyshev expansions and Sturm sequence argumentations whetherp n has some zeros on the unit circle and how many zeros lie on the boundary and in the interior of it. Hence, by a bisection strategy we get the moduli of all zeros to a prescribed accuracy, and additionally we find the arguments as real zeros of a low degree polynomial. In this way we generate starting approximations for all zeros which in a final step are refined by an iterative process of higher order of convergence (e.g. Newton's or Bairstow's method).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 79
    Electronic Resource
    Electronic Resource
    Springer
    Computing 55 (1995), S. 23-42 
    ISSN: 1436-5057
    Keywords: Radiosity ; Monte Carlo ; algorithms ; stochastic convergence ; transillumination method ; stochastic shooting method ; variance reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Die vorgestellten neuen Radiosity Methoden für diffuse Szenen sind besonders geeignet, um die Lichtausbreitung in sehr komplexen Umgebungen in linearer Zeit zu berechnen. Die Verfahren beruhen auf rekursiven Algorithmen, die das Radiosity-Gleichungssystem mittels stochastischer Konvergenz löseu. Approximationen der ‘gathering-’ und ‘shooting-’ Verfahren werden statt einer exakten Berechnung jedes Reflexionsschrittes verwendet. Die Effizienz der Verfahren kann durch geeignete Varianzreduktionsmethoden verbessert werden.
    Notes: Abstract The fast radiosity-type methods for very complex diffuse environments, introduced herein, present a nearly linear-time solution. The outlined procedures rely on recursive algorithms with stochastic convergence for solving the radiosity equation system. Approximations of gathering and shooting at very low computational cost—rather than the exact matrix of a single reflection—are used. The efficiency of the methods will be increased by applying variance reduction techniques.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 80
    Electronic Resource
    Electronic Resource
    Springer
    Computing 55 (1995), S. 43-53 
    ISSN: 1436-5057
    Keywords: Interval analysis ; range computation ; inclusion monotonicity ; Bernstein coefficients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Bekanntlich ist der Wertebereich eines Polynomsf über einem Intervall durch den kleinsten und größten Koeffizienten vonf bezüglich der Bernstein Basis auf dem Intervall eingeschränkt. Dadurch wird eine IntervallerweiterungF vonf definiert, die sogenannte Bernstein Form. In dieser Arbeit zeigen wir, daß die Bernstein Form inklusionsmonoton ist, d. h. wenn.X⊇Y dannF(X)⊇F(Y).
    Notes: Abstract It is well known that the range of polynomialf over an interval is bounded by the smallest and the largest coefficient off with respect to the Bernstein basis over the interval. This defines an interval extensionF off, which is called Bernstein form. In this paper we show that the bernstein form is inclusion monotone, i.e.X⊇Y impliesF(X)⊇F(Y).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 81
    Electronic Resource
    Electronic Resource
    Springer
    Computing 55 (1995), S. 1-22 
    ISSN: 1436-5057
    Keywords: 65L ; 34C ; Reversible integration ; symplectic integrators ; variable step size ; long time integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Werden symplektische oder reversible Integrationsverfahren mit herkömmlichen Schrittweitensteuerungen verwendet, so geht die symplektische, bzw. die reversible Struktur des Problems verloren. In dieser Arbeit wird gezeigt, dass die symplektische Struktur des Verfahrens nur dann erhalten wird, wenn die Schrittweite fast konstant bleibt. Für reversible Verfahren sind echt variable Schrittweiten möglich, die Schrittweite muss jedoch für “gespiegelte” Schritte gleich sein. Es werden verschiedene Wege aufgezeigt, um reversible, variable Schrittweiten zu konstruieren. Numerische Experimente zeigen, dass für das Keplerproblem die neuen Methoden den herkömmlichen Schrittweitensteuerungen oder den symplektischen Verfahren mit konstanter Schrittweite überlegen sind. Insbesondere wächst der globale Fehler linear.
    Notes: Abstract Conventional variable-step implementation of symplectic or reversible integration methods destroy the symplectic or reversible structure of the system. We show that to preserve the symplectic structure of a method the step size has to be kept almost constant. For reversible methods variable steps are possible but the step size has to be equal for “reflected” steps. We demonstrate possible ways to construct reversible variable step size methods. Numerical experiments show that for the Kepler problem the new methods perform better than conventional variable step size methods or symplectic constant step size methods. In particular they exhibit linear growth of the global error (as symplectic methods with constant step size).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 82
    Electronic Resource
    Electronic Resource
    Springer
    Computing 55 (1995), S. 91-111 
    ISSN: 1436-5057
    Keywords: 65F15 (47A56) ; Nonlinear eigenvalue problem ; numerical solution ; condition number
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir betrachten die numerische Lösung des nichtlinearen EigenwertproblemsA(λ)x=0, wobei die MatrixA(λ) in nichtlinearer Weise vom Eigenwertparameter λ abhängt. Einige neue Methoden (die BDS Methoden) werden zusammen mit einer Untersuchung der Bedingungen dieser Methoden vorgestellt. Numerische Beispiele, welche diese Methoden vergleichen, werden präsentiert.
    Notes: Abstract We consider the numerical solution of the nonlinear eigenvalue problemA(λ)x=0, where the matrixA(λ) is dependent on the eigenvalue parameter λ nonlinearly. Some new methods (the BDS methods) are presented, together with the analysis of the condition of the methods. Numerical examples comparing the methods are given.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 83
    Electronic Resource
    Electronic Resource
    Springer
    Computing 55 (1995), S. 55-73 
    ISSN: 1436-5057
    Keywords: 68P [Theory of data] ; 68P05 Data structures ; 68P20 information storage and retrieval ; Object-oriented data models ; ISA hierarchy ; complex objects ; transitive closure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung In den letzten Jahren sind viele objekt-orientierte Datenmodelle vorgeschlagen worden und dieses Gebiet ist zu einem der vielversprechendsten für die Entwicklung neuer Datenbanksysteme geworden. Bei Verwendung von komplexen Datenstrukturen, auf denen eine ISA Hierarchie definiert ist, wird effizientes Speichern and Zugreifen auf Objekte um vieles wichtiger. In dieser Arbeit schlagen wir effiziente mengenorientierte Algorithmen zur Speicherung und zum Zugriff auf komplexe Objekte in einer „Inheritance Hierarchie” vor.
    Notes: Abstract Many object oriented data models have been proposed in the past few years, and this field is one of the most promising for the development of new generation database systems. With complex data structures where an ISA hierarchy has been defined, the problem of efficiently storing and retrieving (a collection of) objects increases its relevance dramatically. This paper proposes efficient set-oriented algorithms for the storage and retrieval of complex objects in an inheritance hierarchy.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 84
    Electronic Resource
    Electronic Resource
    Springer
    Computing 55 (1995), S. 75-89 
    ISSN: 1436-5057
    Keywords: 68Q20 ; 90C39 ; String edit distance ; finte state automaton ; nearest neighbor search ; doctionary lookup
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Es wird ein neuer Algorithmus für die Berechnung der Editierdistanz von Zeichenketten angegeben. Der Algorithmus beruht auf der Annahme, dass eine der beiden zu vergleichenden Zeichenketten ein a priori bekannter Eintrag in einen Wörterbuch ist. Dieser Wörterbucheintrag wird in einer off-line Phase in einen deterministischen endlichen Automaten konvertiert. Für einen gegebenen Automaten und ein Eingabewort entspricht die Berechnung der Editiordistanz einer Traversierung verschiedener Zustände dieses Automaten. Diese Prozedur benötigt Zeit, die lediglich linear von der Länge des Eingabeworts abhängt. Die Zeit ist unabhängig von der Länge des Wörterbucheintrags. Die endlichen Automaten, welche zuN verschiedenen Wörterbucheinträgen gehören, können zu einem einzigen Automaten zusammengefasst werden. Auf diese Weise benötigen die Berechnung der Editierdistanz zwischen dem Eingabewort und jedem Wörterbucheintrag sowie die Bestimmung des nächsten Nachbarn im Wörterbuch lediglich lineare Zeit hinsichtlich der Länge des Eingabeworts. Die Anzahl der Zustände des Automaten ist jedoch von exponentieller Grössenordnung.
    Notes: Abstract A new algorithm for string edit distance computation is given. The algorithm assumes that one of the two strings to be compared is a dictionary entry that is known a priori. This dictionary word is converted in an off-line phase into a deterministic finite state automaton. Given an input string and the automaton derived from the dictionary word, the computation of the edit distance between the two strings corresponds to a traversal of the states of the automaton. This procedure needs time which is only linear in the length of the input string. It is independent of the length of the dictionary word. Given not only one butN different dictionary words, their corresponding automata can be combined into a single deterministic finite state automaton. Thus the computation of the edit distance between the input word and each dictionary entry, and the determination of the nearest neighbor in the dictionary need time that is only linear in the length of the input string. However, the number os states of the automation is exponential.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 85
    Electronic Resource
    Electronic Resource
    Springer
    Computing 55 (1995), S. 163-180 
    ISSN: 1436-5057
    Keywords: 65L05 ; Hopf bifurcation ; Runge-Kutta ; Poincare map
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Um das Verhalten bestimmter Ein- und Mehrschrittverfahren für gewöhnliche Differentialgleichungen an schwach anziehenden Fixpunkten bzw. schwach anziehenden periodischen Lösungen zu untersuchen, wird Rückwärts-Fehleranalyse eingesetzt. Bei vielen Methoden tritt eine Hopf-Verzweigung auf; der Effekt einer adaptiven Gitteranpassung für solche Situationen wird an einem Spezialfall demonstriert.
    Notes: Abstract Backward error analysis is used to analyze the behavior of selected one-step and multi-step methods for ordinary differential equations at weakly attracting fixed points and weakly attracting periodic solutions. For many methods, a Hopf bifurcation for maps occurs. The effect of an adaptive mesh selection procedure on these results is presented for a special case.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 86
    Electronic Resource
    Electronic Resource
    Springer
    Computing 55 (1995), S. 181-189 
    ISSN: 1436-5057
    Keywords: 65N55 ; 65F10 ; Smoothing property ; multi-grid method ; semi-iteration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Eine Modifikation des Lemmas von Reusken wird angegeben. Sie gestattet, im Falle von konvergenten Glättungsiterationen die Konvergenzgeschwindigkeit in die Abschätzung der Glättungseigenschaft mit aufzunehmen. Eine derartige Abschätzung wird bei robusten Mehrgitterverfahren benötigt. Ferner wird ein einfacher semiiterativer Glätter angegeben, der ein asymptotisch besseres Verhalten besitzt.
    Notes: Abstract A modification of the Lemma of Reusken is given. It allows us to improve the estimate of the smoothing property in cases where the contraction number of the iteration is small. This is of importance for robust multi-grid methods. Moreover, we describe a simple semi-iterative smoother with better asymptotic behaviour than for the stationary iterative smoother.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 87
    Electronic Resource
    Electronic Resource
    Springer
    Computing 55 (1995), S. 207-221 
    ISSN: 1436-5057
    Keywords: 65COS ; 65DIS ; Particle methods ; discrepancy estimates ; nonlinear functionals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir betrachten die numerische Berechung nichtlinearer Funktionale von Verteilungsfunktionen, die durch Punktmaße angenähert werden. Zwei Methoden werden beschrieben und Abschätzungen für die Konvergenzgeschwindigkeit werden angegeben. Außerdem werden numerische Resultate für das Entropiefunktional vorgestellt.
    Notes: Abstract We consider the numerical computation of nonlinear functionals of distribution functions approximated by point measures. Two methods are described and estimates for the speed of convergence as the number of points tends to infinity are given. Moreover, numerical results for the entropy functional are presented.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 88
    Electronic Resource
    Electronic Resource
    Springer
    Computing 55 (1995), S. 223-236 
    ISSN: 1436-5057
    Keywords: 65L05 ; 65L06 ; Runge-Kutta methods ; interpolations ; delay differential equations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Beim numerischen Lösen von Differentialgleichungen mit nacheilendem Argument (DDEs) mit Hilfe von stetigen expliziten Runge-Kutta Methoden entstehen Schwierigkeiten, wenn die Argumentverzögerung verschwindet oder zumindest kleiner als die Verfahrensschrittweite wird. In dieser Situation wird der herkömmlich explizite und sequentielle Prozeß der Stufenberechnungen des RK-Schemas ein impliziter und muß überdies iteriert werden. In dieser Arbeit werden einige Iterationsmethoden untersucht und deren Ordnung bestimmt.
    Notes: Abstract In the numerical solution of delay differential equations by a continuous explicit Runge-Kutta method a difficulty arises when the delay vanishes or becomes smaller than the stepsize the method would like to use. In this situation the standard explicit sequential process of computing the Runge-Kutta stages becomes an implicit process and an iteration scheme must be adopted. We will consider alternative iteration schemes and investigate their order.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 89
    Electronic Resource
    Electronic Resource
    Springer
    Computing 55 (1995), S. I 
    ISSN: 1436-5057
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 90
    Electronic Resource
    Electronic Resource
    Springer
    Computing 55 (1995), S. 237-253 
    ISSN: 1436-5057
    Keywords: 65N06 ; Finite difference method ; impulsive partial differential-functional equations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir betrachten Anfangs- und Randwertprobleme von partiellen Impuls-Differential-Funktionalgleichungen erster Ordnung. Wir leiten hinreichende Bedingungen für die Konvergenz einer allgemeinen Klasse von Einschrittmethoden her. Wir nehmen weiters an, daß die gegebenen Funktionen bezüglich ihrer Funktionalargumente einer nichtlinearen Abschätzung vom Perron-Typus genügen. Der Stabilitätsbeweis basiert auf einem Theorem über Differenzen-Funktionalgleichungen, die von einem Impuls-Differential-Funktionalproblem stammen. Grundsätzlich nehmen wir an, daß die betrachteten Funktionen die Volterra-Bedingung erfüllen. Ein numerisches Beispiel wird angeführt.
    Notes: Abstract We consider initial boundary value problems for first order impulsive partial differential-functional equations. We give sufficient conditions for the convergence of a general class of one step difference methods. We assume that given functions satisfy the non-linear estimates of the Perron type with respect to the functional argument. The proof of stability is based on a theorem on difference functional inequalities generated by an impulsive differential-functional problem. It is an essential assumption in our consideration that given functions satisfy the Volterra condition. We give a numerical example.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 91
    Electronic Resource
    Electronic Resource
    Springer
    Computing 55 (1995), S. 191-206 
    ISSN: 1436-5057
    Keywords: 68Q25 ; 68U05 ; Rectangles ; balanced cuts ; separation ; binary space partition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Gegeben sei eine Menge vonn (ggf. überlappenden) isothetischen Hyperrechtecken imd-dimensionalen Raum. Diese Arbeit beschäftigt sich mit Zerlegungen dieser Hyperrechteckmenge durch Schnitthyperebenen, wobei wir annehmen, daß jedes von einer Hyperebene geschnittene Hyperrechteck in zwei nicht-überlappende Hyperrechtecke zerschnitten wird. Wir untersuchen das Verhalten einiger Balancierungskriterien für Schnitte und präsentieren optimale and praktikable Algorithmen zur Berechnung der entsprechenden balancierten Schnitte. Schließlich geben wir auch scharfe Worst-case-Schranken für die bestmöglich erreichbare Qualität der balancierten Schnitte an.
    Notes: Abstract We are given a set ofn d-dimensional (possibly intersecting) isothetic hyperrectangles. The topic of this paper is the separation of these rectangles by means of a cutting isothetic hyperplane. Thereby we assume that a rectangle which is intersected by the cutting plane iscut into two non-overlapping hyperrectangles. We investigate the behavior of several kinds of balancing functions, as well as their linear combination and present optimal and practical algorithms for computing the corresponding balanced cuts. In addition, we give tight worst-case bounds for the quality of the balanced cuts.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 92
    Electronic Resource
    Electronic Resource
    Springer
    Computing 55 (1995), S. 271-288 
    ISSN: 1436-5057
    Keywords: 65F10 ; Finite elements ; multigrid methods ; error control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir behandeln das Problem einer adaptiven Fehlerkontrolle bei Finite-Elemente-Methoden unter Enschluß des Fehlers, der durch ungenaue Lösung der diskreten Gelichungen entsteht. Wir beweisen A-posteriori-Fehlerabschätzungen für ein elliptisches Modellproblem, welches mit linearen finiten-Elementen diskretisiert wird. Die diskreten Gleichungen werden mit Hilfe des kanonischen Finite-Elemente-Mehrgitterverfahrens gelöst. Die Beweise beruhen auf der Kombination der «starken” stabilitätseigenschaft des zugrundeliegenden Differentialoperators und der Galerkin-Orthogonalität sowohl des Finite-Elemente-als auch des Mehrgitterverfahrens.
    Notes: Abstract We consider the problem of adaptive error control in the finite element method including the error resulting from, inexact solution of the discrete equations. We prove a posteriori error estimates for a prototype elliptic model problem discretized by the finite element with a canomical multigrid algorithm. The proofs are based on a combination of so-called strong stability and, the orthogonality inherent in both the finite element method can the multigrid algorithm.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 93
    Electronic Resource
    Electronic Resource
    Springer
    Computing 55 (1995), S. 289-304 
    ISSN: 1436-5057
    Keywords: 65N15 ; 65N30 ; 65N50 ; Adaptive mesh refinement ; a posteriori error estimate ; nonlinear Poisson equation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir entwickeln adaptive Methoden zur Berechnung von Finite Elemente-Lösungen der Partiellen Differentialgleichung −Δu=f(u) auf einem beschränktem Gebiet Ω ⊆ ℝ2. In der Praxis arbeitet man mit einer Approximationf h vonf, was zu falschen Ergebnissen führen kann, wenn man den zugehörigen Approximationsfehler auf dem groben Gitter nicht mitberücksichtigt. Wir verwenden eine Strategie, die zu Beginn der Iteration robust aber weniger effizient ist und gehen zu effektiveren Methoden über, falls gewisse Sättigungsbedingungen erfühlt sind. Dazu leiten wir a posteriori Fehlerschranken und a posteriori Sättigungsbedingungen her, um die Qualität der numerischen Lösung zu beurteilen.
    Notes: Abstract Our goal is to develop adaptive strategies in order to obtain finite element solutions of the partial differential equation-Δu=f(u) in a bounded domain Ω ⊆ ℝ2. In practice one works with an approximationf h off. But this may give wrong results if we do not control the coresponding approximation error on coarse girds. In this work we develop a strategy that is robust, but less efficient, in the beginning of the adaptive algorithm and switches to a more efficient procedure if certainsaturation conditions are satisfied. The results are based on a posteriori saturation criterial that measure the quality of the approximation solution.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 94
    Electronic Resource
    Electronic Resource
    Springer
    Engineering with computers 11 (1995), S. 94-102 
    ISSN: 1435-5663
    Keywords: Rational cubic ; Bernstein-Bézier ; Shape control ; Tension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper is concerned with the problem of fitting curves and surfaces, for computer aided design (CAD), via an ordered set of control points, so that the result is satisfactory for the user's needs. Piecewise rational functions with cubic numerator and quadratic denominator are used in the construction of the scheme, in such a way that the descriptions of the parameters control the shape of the picture in the desired area. A general solution is obtained for points inN-space, although the scheme is only meaningful in the cases whereN=2 andN=3.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 95
    Electronic Resource
    Electronic Resource
    Springer
    Engineering with computers 11 (1995), S. 145-156 
    ISSN: 1435-5663
    Keywords: Database ; Date fusson ; Date model ; Information architecture ; Information model ; Manufacturing ; Sensors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Data fusion is the integration and analysis of data from multiple sensors to develop a more accurate understanding of a situation and determine how to respond to it. Although data fusion can be applied in many situations, this paper focuses on its application to manufacturing and how it changes some of the more traditional, less adaptive information models that support the design and manufacturing functions. The paper consists of four parts. The first section explains what data fusion is and its impact on manufacturing. The second section describes what an information system architecture is and explains the natural language-based information modeling methodology used by this research project. The third section identifies the major design and manufacturing functions, reviews the information models required to support them, and then shows how these models must be extended to support data fusion. The fourth section discusses the future directions of this work.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 96
    Electronic Resource
    Electronic Resource
    Springer
    Engineering with computers 11 (1995), S. 167-172 
    ISSN: 1435-5663
    Keywords: Concurrent engineering ; Configuration management ; Data model ; Design Process ; Engineering data management ; Product data management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract In order to make the traditional product structure tree representation amenable to concurrent engineering relationships likeperspective-of anddependent-on have to be added to the essentialpart-of relationship. Complex data can be held in proprietary formats, while simple data will be in a common representation for direct access by diverse disciplines. Coordination among team members in a project can be carried out using such a model. Besides, a virtually unified view of all the data is possible, though they may lie in distributed and heterogeneous data bases. A very necessary characteristic of such a model is that its time evolution should be easy to represent in order to reflect the dynamic nature of product development, where the model itself, and not merely the data values change. Managing versions is also facilitated by the comprehensive structure of the Unified Product Data Model (UPDM).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 97
    Electronic Resource
    Electronic Resource
    Springer
    Engineering with computers 11 (1995), S. 227-245 
    ISSN: 1435-5663
    Keywords: Conceptual design ; Design process ; Design studies ; Engineering information systems ; Product data
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper identifies requirements for an engineering design information management system. Future CAD systems must support a wide range of activities — such as definition, manipulation and analyses of complex product information models. These models represent not only conventional data associated with current CAD applications, but also design information characterizing the correlations between the requirements, functions, behaviors and physical form of the product. Such functionality is important for both the individual designer and the design organization, as the need to manage information as a corporate asset is becoming a critical component of business strategy. This paper explores these needs using two design studies. The first study illustrates some major concepts relative to non-routine design activities, while the second study focuses on the routine design activities relative to organization interactions. These studies were used to elicit high level requirements which serve as the basis for the development of prototype software systems. These prototypes are briefly introduced here.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 98
    Electronic Resource
    Electronic Resource
    Springer
    Engineering with computers 11 (1995), S. 213-226 
    ISSN: 1435-5663
    Keywords: Communication channel ; Communication path ; Data attribute ; Design object ; Method group ; Object-oriented ; Receiving interface ; Relationship ; Relationship attribute ; Sending method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Object-oriented principles have introduced several useful concepts for developing complex software systems. As a result, several methodologies have been suggested for the overall design of software systems based on these concepts. Methodologies and frameworks for designing objects that are to be part of the software systems are currently lacking. This paper proposes anobject design framework andmethodology, which utilizes the object-oriented concepts, for planning, organizing and designing structural engineering design objects. Design objects in an integrated structural engineering system are complex and often related to each other in various different ways. The paper also identifies several important relationships among structural engineering design objects. These relationships serve as communication channels through wich design objects send messages to and receive responses from each other. Several examples, drawn from reinforced concrete structures, will be presented to demonstrate the object design methodology and to illustrate how the framework is effective in reducing the complexity of design objects in an integrated structural engineering system.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 99
    Electronic Resource
    Electronic Resource
    Springer
    AI & society 9 (1995), S. 18-28 
    ISSN: 1435-5655
    Keywords: Ethics ; Science ; Technology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In the paper, three propositions are put forward. First, that intellectual structures of wide scope commonly lead to conclusions which are ethically unacceptable; secondly that the ethically unacceptable consequences of science arise from one particular presupposition which it adopts, namely that of causality; thirdly, that causality is no essential part of science.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 100
    Electronic Resource
    Electronic Resource
    Springer
    AI & society 9 (1995), S. 29-42 
    ISSN: 1435-5655
    Keywords: Skills ; Deskilling ; Communication ; Control ; Privacy ; Identity ; Ethical neutrality ; Discourse ; Responsibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper first illustrates what kind of ethical issues arise from the new information, communication and automation technology. It then argues that we may embrace the popular idea that technology is ethically neutral or even ambivalent without having to close our eyes to those issues and in fact, that the ethical neutrality of technology makes them all the more urgent. Finally, it suggests that the widely ignored fact of normal responsible behaviour offers a new and fruitful starting point for any future thinking about such issues.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...