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  • Articles  (29)
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  • Springer  (29)
  • American Geophysical Union
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  • 1
    Electronic Resource
    Electronic Resource
    Look ahead job demanding for improving job shop performance (1997)
    Springer
    OR spectrum 19 (1997), S. 23-29 
    Details
    ISSN: 1436-6304
    Keywords: Job shop scheduling ; dispatching rules ; coordination ; look ahead information ; simulation ; Werkstattsteuerung ; Steuerungsregeln ; Koordination ; Vorausschauende Informationen ; Simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Description / Table of Contents: Zusammenfassung In diesem Beitrag wird ein neuartiger Ansatz zur Koordination dezentraler Werkstattsteuerungsregeln vorgestellt und mit Hilfe einer Simulationsstudie analysiert. Die Koordination basiert auf vorausschauenden Informationen und enthält einen Auftragsnachfrage-/-angebotsmechanismus. Die Simulations-experimente zeigen, daß durch den Einsatz des Koordinationsmechanismus die Leistung herkömmlicher Steuerungsregeln signifikant verbessert wird.
    Notes: Abstract In this paper a new coordination approach for decentralized job shop scheduling rules is presented and analyzed in a simulation study. The coordination is based on look ahead information and contains a mechanism for demanding and supplying jobs. The simulation experiments show that the performance of conventional scheduling rules is significantly improved using the coordination mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01539802
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  • 2
    Electronic Resource
    Electronic Resource
    Look ahead job demanding for improving job shop performance (1997)
    Springer
    OR spectrum 19 (1997), S. 23-29 
    Details
    ISSN: 1436-6304
    Keywords: Key words: Job shop scheduling ; dispatching rules ; coordination ; look ahead information ; simulation ; Schlüsselwörter: Werkstattsteuerung ; Steuerungsregeln ; Koordination ; Vorausschauende Informationen ; Simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Description / Table of Contents: Zusammenfassung. In diesem Beitrag wird ein neu-artiger Ansatz zur Koordination dezentraler Werkstattsteuerungsregeln vorgestellt und mit Hilfe einer Simulationsstudie analysiert. Die Koordination basiert auf vorausschauenden Informationen und enthält einen Auftragsnachfrage-/-angebotsmechanismus. Die Simulations- experimente zeigen, daß durch den Einsatz des Koordinationsmechanismus die Leistung herkömmlicher Steuerungsregeln signifikant verbessert wird.
    Notes: Abstract. In this paper a new coordination approach for decentralized job shop scheduling rules is presented and analyzed in a simulation study. The coordination is based on look ahead information and contains a mechanism for demanding and supplying jobs. The simulation experiments show that the performance of conventional scheduling rules is significantly improved using the coordination mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01539802
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  • 3
    Electronic Resource
    Electronic Resource
    Simulation of a polymer electrolyte fuel cell electrode (1997)
    Springer
    Journal of applied electrochemistry 27 (1997), S. 1254-1264 
    Details
    ISSN: 1572-8838
    Keywords: PEFC ; simulation ; gas diffusion electrode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract A detailed one dimensional dynamic model of a gas diffusion electrode as part of a complete fuel cell model is presented. Various effects of parameter changes are considered. Comparison of experimental results and simulation is performed and a new approach to simulation of a complete current voltage curve is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018488021355
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  • 4
    Electronic Resource
    Electronic Resource
    Convection-diffusion of solutes in dynamic media (1997)
    Springer
    Adsorption 3 (1997), S. 41-54 
    Details
    ISSN: 1572-8757
    Keywords: liquid crystals ; moving bed system ; simulation ; purification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract We investigate convective-diffusive transport of a solute through a medium with properties that can be externally modulated in space and time. In particular, we focus on the effect of a front—a sharp transition in the convective velocity (v) and diffusivity (D)—on the evolution of the solute concentration profile. Numerical results show that by suitably moving the front during the process an anti-dispersive effect may be realized, in which the solute accumulates in a thin region close to the moving boundary. Our computations take into account the realistic case of a front having a small but finite thickness, and we find that the width of the concentration profile scales as $$\left( {1/\sqrt {Pe} } \right)$$ , where Pe is the Péclet number. This is in sharp contrast to the 1/Pe scaling observed for the ideal case of the singular front assumed in previous work. The effect of the thickness of the front and the magnitude of the drop inv andD, on the solute concentration profile has also been studied. These results are relevant in order to implement and optimize protocols that apply an externally controlled moving boundary for the purpose of separation. We also present experimental results characterizing solute transport across a stationary front, expected to display many features needed in a model for moving fronts. The concentration profile of electrophoretically mobile BSA-FITC within the boundary layer at a polyacrylamde gel-buffer interface were visualized by epifluorescence microscopy. Measured boundary layer thickness exceeded that predicted for even a finite interface, indicating that the length scale associated with real boundaries is relevant to the modeling problem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01133006
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  • 5
    Electronic Resource
    Electronic Resource
    Experimental evaluation of the classificatory performance of mathematical programming approaches to the three-group discriminant problem: The case of small samples (1997)
    Springer
    Annals of operations research 74 (1997), S. 191-209 
    Details
    ISSN: 1572-9338
    Keywords: integer programming ; discriminant analysis ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract Although there have been several journal articles on the classificatory performance of mathematical programming approaches to the two-group discriminant problem, there has been no simulation study on the classificatory performance of mathematical programming approaches to the multiple-group problem reported in the literature. This study reports the results of a simulation experiment on the classificatory performance of a single-function and a multiple-function mathematical programming model relative to that of the standard parametric procedures for the three-group problem with small training samples. The effect of second-order terms on the classificatory performance of the mathematical programming models for the three-group problem is also investigated. Furthermore, this study theoretically examines the range of parameter values of a multiple-function mathematical programming model for which its number of misclassifications in the training sample cannot exceed that of a single-function model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018918320541
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  • 6
    Electronic Resource
    Electronic Resource
    Enhancing graphical simulation output using cluster analysis (1997)
    Springer
    Annals of operations research 74 (1997), S. 321-332 
    Details
    ISSN: 1572-9338
    Keywords: simulation ; modeling ; aerospace ; air route structure ; free flight ; clustering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract Recent work performed for the Federal Aviation Administration to support the development of future concepts of air traffic management has involved simulation modeling of patterns of airspace usage by commercial and business air traffic. The objective of these efforts has been to investigate the impacts of a pattern of airspace usage known as "free flight", whereby pilots and flight dispatchers have much more freedom to choose, say, direct or wind-optimal routing through airspace. One of the figures of merit investigated is a count of "convergence pairs" as a measure of the complexity of various traffic patterns. These are cases when aircraft in the simulation model fly close to each other. Interestingly, geographic plots of convergence pairs accumulated over time bring out certain features or patterns of congested air traffic flows or flight alignments. However, these plots are also thick with "noise" or extraneous convergence pairs, whose presence detracts from the ability to perceive congested air traffic flows. Cluster analysis has been found to be an effective method of filtering these displays so that the congested flow features are discernible. The process developed for this purpose is based on a two-pass clustering approach. The process has worked well for the simulation modeling performed to date. Classification of the locations of convergence pairs into congested flow corridors is visually appealing, and has helped distinguish differences in contrasting scenarios of airspace usage. The paper presents graphical results and describes the clustering algorithms employed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018986808246
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  • 7
    Electronic Resource
    Electronic Resource
    A System Dynamics Model of Planned Organizational Change (1997)
    Springer
    Computational & mathematical organization theory 3 (1997), S. 151-171 
    Details
    ISSN: 1572-9346
    Keywords: organizational performance ; planned organizational change ; resistance to change ; system dynamics ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This paper suggests that an induction of change program leads to atemporary impairment of organizational performance. A System Dynamics Modelportrays the process of planned organizational change. A set of keyvariables that facilitate or impede change is identified, quantified, andintegrated into the model. Three data sets, reproduced by simulation,demonstrate that the model is internally consistent and empiricallyadequate. The paper discusses theoretical and practical implications of the‘initial dip’ phenomenon in processes of planned change.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009664618421
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  • 8
    Electronic Resource
    Electronic Resource
    Estimation and testing in least absolute value regression with serially correlated disturbances (1997)
    Springer
    Annals of operations research 74 (1997), S. 239-257 
    Details
    ISSN: 1572-9338
    Keywords: autocorrelation ; L 1 regression ; least absolute deviations ; robust regression ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract Least absolute value (LAV) regression provides a robust alternative to least squares, particularly when the disturbances follow distributions that are nonnormal and subject to outliers. While inference in least squares estimation is well-understood, inferential procedures in the context of LAV estimation have not been studied as extensively, particularly in the presence of non-independent disturbances. In this work, we study three alternative significance test procedures in LAV regression, along with two approaches used to correct for serial correlation. The study is based on large-scale Monte Carlo simulations, and comparisons are made based on both observed significance levels and power.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018974405520
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  • 9
    Electronic Resource
    Electronic Resource
    Model misspecification in Data Envelopment Analysis (1997)
    Springer
    Annals of operations research 73 (1997), S. 233-252 
    Details
    ISSN: 1572-9338
    Keywords: Data Envelopment Analysis ; model specification ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract The use of Data Envelopment Analysis for estimating comparative efficiency has become widespread, and there has been considerable academic attention paid to the development of variants of the basic DEA model. However, one of the principal weaknesses of DEA is that - unlike statistically based methods - it yields no diagnostics to help the user determine whether or not the chosen model is appropriate. In particular, the choice of inputs and out-puts depends solely on the judgement of the user. The purpose of this paper is to examine the implications for efficiency scores of using a misspecified model. A simple production process is set up. Simulation models are then used to explore the effects of applying misspecified DEA models to this process. The phenomena investigated are: the omission of significant variables; the inclusion of irrelevant variables; and the adoption of an inappropriate variable returns to scale assumption. The robustness of the results is investigated in relation to sample size; variations in the number of inputs; correlation between inputs; and variations in the importance of inputs. The paper concludes that the dangers of misspecification are most serious when simple models are used and sample sizes are small. In such circumstances, it is concluded that it will usually be to the modeller's advantage to err on the side of including possibly irrelevant variables rather than run the risk of excluding a potentially important variable from the model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018981212364
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  • 10
    Electronic Resource
    Electronic Resource
    Reformulation for Latent-Image Formation Model in Photolithography Using Numerical Absorbing Boundary Condition (1997)
    Springer
    Optical review 4 (1997), S. 700-706 
    Details
    ISSN: 1349-9432
    Keywords: photolithography ; simulation ; topography scattering ; numerical absorbing boundary condition ; finite-element method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A method for simulating latent image formation in a photoresist illuminated by an arbitrary imaging system is presented. A variational formulation for light scattering, which does not depend on a specific configuration of the imaging system, is derived and solved using the finite-element method. The perfectly matched layer absorbing boundary condition is applied to take wave propagation in the infinite region surrounding the photoresist into account. The validity of the method is examined by comparing the results with those made by the vertical propagation model and the previous two-dimensional models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s10043-997-0700-2
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  • 11
    Electronic Resource
    Electronic Resource
    A Multi-Spectral Polarimeter for Measurements of Direct Solar and Diffused Sky Radiation: Calibration and Measurements (1997)
    Springer
    Optical review 4 (1997), S. 496-501 
    Details
    ISSN: 1349-9432
    Keywords: polarization ; calibration ; Langley plot ; light scattering ; aerosol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A multi-spectral polarimeter (FPR1000) is designed to measure the radiance and degree of polarization of the sky radiation as well as the extinction of solar irradiance using the same optical system. This enables us to make consistent measurements of the direct solar and diffused sky radiation. Measurements are made at the same wavelength regions as Polarization and Directionality of the Earth’s Reflectances (POLDER) and Ocean Color and Temperature Scanner (OCTS) onboard Advanced Earth Observing Satellite (ADEOS). Based on measurements for the Langley plot calibration made at Mauna Loa Observatory, the calibration constants are obtained by considering the effect of absorption by water vapor and uniformly mixed gas. Preliminary analyses of the measurements of sky radiation and direct solar irradiance carried out in the western part of the Pacific Ocean are presented. Combined measurements of the extinction of solar irradiance, and the radiance and degree of polarization of sky radiation could be useful in improving retrieval of optical characteristics of aerosol and for atmospheric correction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s10043-997-0496-0
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  • 12
    Electronic Resource
    Electronic Resource
    Geometric Phase Observation with Dispersed Fringes (1997)
    Springer
    Optical review 4 (1997), S. 593-595 
    Details
    ISSN: 1349-9432
    Keywords: geometric phase ; interferometry ; polarization ; Michelson interferometer ; stellar interferometer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Geometric and dynamic phases are separately observed using dispersed fringes, and the difference between them is clearly demonstrated. Independence of geometric phase of wavelength is straightforwardly shown in the dispersed fringe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s10043-997-0593-0
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  • 13
    Electronic Resource
    Electronic Resource
    CCD Polarimetric Imaging Of Comet Hale-Bopp (C/1995 O1) (1997)
    Springer
    Earth, moon and planets 78 (1997), S. 365-371 
    Details
    ISSN: 1573-0794
    Keywords: Comet Hale-Bopp ; cometary dust ; scattering ; polarization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Polarimetric observations of the light scattered by dust have been carried out at Pic-du-Midi Observatory with the 2 m telescope in June and September–October 1996, and at Haute-Provence Observatory with the 0.80 m telescope in April 1997. They cover a total number of 11 nights and a large (6.9°–47.7°) phase angle range. The spatial resolution allows to underline structures in the coma, as well in the brightness images as in the polarization maps, with a correlation between the regions of bright structures and the regions of higher polarization. A clear difference appears between the sunward and antisunward side, with higher polarization on the antisunward side. The phase angle coverage allows us to obtain a polarimetric phase curve for the whole coma and to compare it with other cometary phase curves. The degree of polarization is higher for Hale-Bopp than for the comets previously observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006206613959
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  • 14
    Electronic Resource
    Electronic Resource
    Imaging polarimetry of comet Hale-Bopp (C/1995 O1) around perihelion (1997)
    Springer
    Earth, moon and planets 78 (1997), S. 359-364 
    Details
    ISSN: 1573-0794
    Keywords: Comet Hale-Bopp ; polarization ; dust
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The polarization distribution of the inner coma of comet Hale-Bopp was measured by CCD imaging around perihelion. The dust shell positions correlate well with relative maxima of polarization. The images taken in the I-band identify different shell systems, each showing individual polarization properties. This could be related to differences in the dust properties of the associated jets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006250412142
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  • 15
    Electronic Resource
    Electronic Resource
    Near-Infrared Photometric And Polarimetric Observations Of Comet Hale-Bopp (1997)
    Springer
    Earth, moon and planets 78 (1997), S. 353-358 
    Details
    ISSN: 1573-0794
    Keywords: Comet ; polarization ; dust ; jet ; infrared
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Near-infrared photometric and polarimetric observations of comet Hale-Bopp (1995 O1) using KONIC (Kiso Observatory Near-Infrared Camera) are reported. Observations were carried out on March 18 UT and April 26 UT 1997, when the heliocentric distances of the comet were 0.94 and 1.02 AU, and the phase angles were 48.5 deg and 32.9 deg, respectively. In the J, H, and K′ bands, we obtained linear polarization of the near-nucleus region of 16.4 ± 1.2, 18.8 ± 1.3, and 15.1 ± 0.9 percent on March 18UT and 7.1 ± 1.1, 8.9 ± 1.0, and 6.9 ± 0.6 percent on April 26, respectively. These values were higher than those observed for 1P/Halley. The maximum polarization was found at H band on both dates. Polarization maps showed higher polarization regions toward the anti-solar direction in the J and H bands. No distinct correlation was found between high polarization regions and bright regions. The projected expansion velocity of the arc structure of the dust jet was 375 ± 35.7 m/s on 17–19 March. The periodicity was found to be 11.1 ± 2.8 hours.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006298327163
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  • 16
    Electronic Resource
    Electronic Resource
    Images Of Polarization And Colour In The Inner Coma Of Comet Hale-Bopp (1997)
    Springer
    Earth, moon and planets 78 (1997), S. 373-379 
    Details
    ISSN: 1573-0794
    Keywords: Comet C/1995 O1 (Hale-Bopp) ; dust ; colour ; polarization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract On March 31 and April 1, 1997, simultaneous photometry and polarimetry of comet Hale-Bopp's dust was conducted with the two-channel focal reducer of the Max-Planck-Institute for Aeronomy attached to the 2 m telescope of Pik Terskol Observatory (Northern Caucasus). Interference filters at642 nm and 443 nm selected red and blue narrow-band continuum windows. The observations have been averaged over the one hour of timethe comet could be observed. The polarization maps cover an area of about1 arcmin2 around the nucleus. The values of polarization degree measured close to the nucleus agree very well with observations obtained with aperture polarimetry. They are lower than in the surrounding coma by about 1%. In our field of view the polarization increases along the sun-comet line from the solar to the antisolar side by about 3%. The dust shells are visible in the polarization images. The polarization in the shells is higher by 1 to 2%and this increase is higher in the red than in the blue range. Therefore the ratio of red to blue polarization (≈ 1.2) increases in the shells by ≈ 0.03. In principle, the polarization excess in the shells, the ratio of red/blue polarization and the higher integrated polarization as compared to other comets can be explained by an excess of particles of radius of about 0.1 μm. Such particles, however, are subject to strong radiation pressure and will be pushed back into the tail before they reach the observed location of the shells. Real Rayleigh particles cannot explain the observed increase in the ratio of red/blue polarization. One therefore cannot exclude the possibility that the excess polarization in the shells is caused by fluffy aggregates via effects which are presently not well understood. The colour map shows features not well related to intensity and polarization, perhaps another dust shell of a different particle size.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006214930797
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  • 17
    Electronic Resource
    Electronic Resource
    Observations Of Scattered Light From Cometary Dust And Their Interpretation (1997)
    Springer
    Earth, moon and planets 79 (1997), S. 221-245 
    Details
    ISSN: 1573-0794
    Keywords: Comets ; dust ; colour ; polarization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract This review begins with a discussion of the techniques needed for observations of scattered light from cometary dust. After an introduction into the basic concepts of the scattering process, observations of the phase curves of brightness, colour and polarization are covered. Images of colour and polarization are presented and the observed relation of colour and polarization in jets and shells is discussed. The interpretation of the measurements is based on the power law size distributions of dust grains observed from space. The power index must lie between 2 and 4 to provide the mass budget and visibility of the dust coma in accordance with the basic facts of cometary physics. Application of mechanical (radiation pressure) theory to cometary images allows us to derive related power law distributions for comets not explored by spacecraft. Grain scattering models are presented and compared with observations. A prediction is made of the spatial distribution of Stokes parameters U and V in the presence of aligned particles. Up to now such patterns have not been observed. Future work should include the exploration of comets at small and possibly very small phase angles and a detailed comparison of polarization and colour images of comets with thermal images and with models based on mechanical theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006249703639
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  • 18
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    Aperture Polarimetry And Photometry Of Comet Hale-Bopp (1997)
    Springer
    Earth, moon and planets 78 (1997), S. 347-352 
    Details
    ISSN: 1573-0794
    Keywords: Comets ; comet Hale-Bopp ; polarization ; dust
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We present results of polarimetric and photometric observations of bright comet C/1995 O1 (Hale-Bopp) obtained at the 0.7 m telescope of Kharkov University Observatory from June 18, 1996 to April 24, 1997. The IHW and HB comet filters were used. The C2 and C3 production rates for Hale-Bopp are more than one order of magnitude larger and the dust production rates are more than two orders of magnitude larger than the Halley ones at comparable distances. Hence, Hale-Bopp was one of the most dusty comets. The average UC-BC and BC-RC colours of the dust were −0.02 and 0.13 mag, respectively. The polarization of comet Hale-Bopp at small phase angles of 4.8–13.0° was in good agreement with the date for comet P1/Halley at the same phase angles in spite of the fact that the heliocentric distances of comments differed nearly twice. However, at intermediate phase angles of 34–49° the polarization of comet Hale-Bopp was significantly larger than the polarization of the other dusty comets. It is the first case of such a large difference found in the continuum polarization of comets. The wavelength dependence of polarization for Hale-Bopp was steeper than for other dusty comets. The observed degree of polarization for the anti-sunward side of the coma was permanently higher than that for the sunward shell side. The polarization phase dependence of Hale-Bopp is discussed and compared with the polarization curves for other dusty comets. The peculiar polarimetric properties of comet Hale-Bopp are most likely caused by an over-abundance of small or/and absorbing dust particles in the coma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006246310324
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  • 19
    Electronic Resource
    Electronic Resource
    Phase-Only Modulation with a Twisted Nematic Liquid Crystal Panel for a Reconfigurable Grating (1997)
    Springer
    Optical review 4 (1997), S. 395-401 
    Details
    ISSN: 1349-9432
    Keywords: spatial light modulator ; twisted nematic liquid crystal panel ; polarization ; grating ; reconfigurable
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A single-path transmission type twisted nematic liquid crystal panel appears to achieve nearly phase-only spatial light modulation when placed between a properly aligned polarizer and analyzer. We obtained more than π phase delay with the equipment whose retardation was less than π.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s10043-997-0395-4
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  • 20
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    Analysis and design of mechanical crack arrestors for gas pipeline (1997)
    Springer
    Acta mechanica solida Sinica 10 (1997), S. 283-298 
    Details
    ISSN: 0894-9166
    Keywords: fracture mechanics ; finite element ; simulation ; curved beam ; pipeline ; arrest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Mechanical arrestors are frequently used in gas transmission pipelines to prevent the possibility of long running cracks. These arrestors have the effect of reducing the pipe from opening as the crack passes. This decreases the available crack driving force and, as a result, crack arrest may take place. This essentially is a second line of defence against catastrophic failure in the event crack initiation cannot always be prevented. A novel analyzing method presented in this paper has been developed to investigate the suitability of these crack arrestors. This is based on a fluid/structure/fracture interaction package, PFRAC. A dynamic finite element approach has been developed for a three dimension curved beam with initial plane curvature, which has been implemented in PFRAC to simulate the behaviour of the arrestor. The contact conditions between the pipe wall and the arrestor, along with the various computational procedures, are described. Several numerical results for a cracked pipe with arrestors are presented and compared with those for pipes without arrestors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02207792
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  • 21
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    Material fracture toughness determination for polyethylene pipe materials using small scale test results (1997)
    Springer
    Acta mechanica Sinica 13 (1997), S. 63-80 
    Details
    ISSN: 1614-3116
    Keywords: fracture mechanics ; pipeline ; experiment ; finite element ; simulation ; fracture toughness ; critical pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The Small-Scale Steady State (S4) test has been recently developed in order to assess the fracture behaviour of polyethylene (PE) gas distribution pipe material during rapid axial crack propagation. Based on an investigation of the S4 test, a simulation model of S4 test has been developed. This paper describes the use of the results obtained from the S4 test and program modified from PFRAC (Pipeline Fracture Analysis Code) to evaluate the fracture toughness of the material,G, which could not be directly obtained from the test, and to predict critical pressure,p c , for rapid crack propagation (RCP) in a full scale PE pipe. The algorithms for contact conditions are developed to consider the opening pipe wall impact against a series containment rings and the capabilities of PFRAC are also extended. WhenG d is evaluated, investigations are made on the effect of temperature, wall thickness and crack velocity. In addition, procedures to evaluate the critical pressure for the S4 test pipe are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02487832
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    A Simple and Robust Lognormal Estimator (1997)
    Springer
    Mathematical geology 29 (1997), S. 993-1008 
    Details
    ISSN: 1573-8868
    Keywords: lognormal estimator ; lognormal kriging ; simulation ; conditional unbiasedness ; robustness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract In an open pit mine, the selection of blocks for mill feed necessitates the use of a conditionally unbiased estimator not only to maximize profits, but also to predict precisely the grades at the mill. Estimation of blocks usually is done using a series of blasthole assays on a regular grid. In many instances, the blasthole grades show a lognormal-like distribution. This study examines an estimator based on the hypothesis of bilognormality between the true block grade and the estimate obtained using the blastholes. The properties of the estimator are established and the estimator is proven to be conditionally unbiased. It is almost as precise as the lognormal kriging estimator when the points are multilognormal. However, it is more precise than lognormal krigings when only univariate lognormality is present or when the distribution is not exactly lognormal. The estimator also is shown to be robust to errors in the specifications of the variogram model or of the expectation of Z. Contrary to lognormal krigings, the estimator does only a slight correction to the original estimate obtained using the blastholes assays.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022357502767
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    Relativistic wave packing and quantization (1997)
    Springer
    Speculations in science and technology 20 (1997), S. 21-32 
    Details
    ISSN: 1573-9309
    Keywords: Quantum ; classical ; vacuum ; polarization ; electromagnetic.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Natural Sciences in General , Technology
    Notes: Abstract It is shown that an alternative version of Schro¨dinger theory based only on classical physical concepts makes possible a simple and direct derivation of Sommerfeld's fine-structure formula in an external field independent way in the general context of bound electronic states. It is thus demonstrated that this formula is of classical origin and of much greater generality than had previously been thought.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018504401502
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    UV Photopolarimetric Imaging of C/1995 O1 (Hale-Bopp) with the Wide Field Imaging Survey Polarimeter (WISP) (1997)
    Springer
    Earth, moon and planets 78 (1997), S. 161-167 
    Details
    ISSN: 1573-0794
    Keywords: Comets ; dust ; polarization ; photochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We report on the reduction and analysis of UVpolarimetric images of CI (λ1657 Å) and dust continuum (2696 Å emissions from C/1995 O1 (Hale-Bopp) taken using the Wide Field Imaging Survey Polarimeter (WISP) sounding rocket on 8 April, 1997. These observations represent the first imaging polarimetry of comets in the UV, and were performed in consort with ground based measurements of gas and dust polarization and distribution. The continuum results show 9% polarization across the image field with a polarization phase angle close to the 129° prediction. Comparison with ground based data implies minimal color dependence for Hale-Bopp in either the degree of polarization and in the position angle. The carbon polarimetry implies that most production occurs in the dense inner coma, and that it leaves that area in thermodynamic equilibrium. Its radial profile further constrains the carbon outflow speed to be sufficient to travel ≥5 × 106 km without photoionization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006297428846
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    Polarimetry Of Comet Hale-Bopp: Linear And Circular Polarization, Stellar Occultation (1997)
    Springer
    Earth, moon and planets 78 (1997), S. 381-386 
    Details
    ISSN: 1573-0794
    Keywords: Comets ; comet Hale-Bopp ; polarization ; grains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Comet Hale-Bopp was observed with the 2.6-m and 1.25-m telescopes of the Crimean Astrophysical Observatory on March 9 and 11, 1997. We determined the linear and circular polarization in the coma. For the dust coma, the linear polarization varied from 7.8% to 12.4%. The degree of circular polarization was always negative and did not exceed 0.3% with an accuracy of ±0.04% on average. The passage of a bright star through the cometary coma was monitored with polarimetry and photometry. The wavelength dependence and spatial variations of optical thickness of dust are obtained from the stellar occultation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006266914867
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    Simulation Techniques for the Manufacturing Test of MCMs (1997)
    Springer
    Journal of electronic testing 10 (1997), S. 137-149 
    Details
    ISSN: 1573-0727
    Keywords: simulation ; yield ; SMT ; MCM ; board ; test ; DFT ; DFM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Simulation techniques used in the Manufacturing Test SIMulator(MTSIM) are described. MTSIM is a Concurrent Engineering tool used tosimulate the manufacturing test andrepair aspects of boards and MCMs from design concept through manufacturing release. MTSIM helps designers select assemblyprocess, specify Design For Test (DFT) features, select board testcoverage, specify ASIC defect level goals, establish productfeasibility, and predict manufacturing quality and cost goals. A newyield model for boards and MCMs which accounts for theclustering of solder defects is introduced and used topredict the yield at each test step. In addition, MTSIMestimates the average number of defects per board detected at eachtest step, and estimates costs incurred in test execution, faultisolation and repair. MTSIM models were validated withhigh performance assemblies at Hewlett-Packard (HP).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008286901817
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    Zeeman transitions in deuterium atoms induced by ultra-relativistic electrons (1997)
    Springer
    Hyperfine interactions 110 (1997), S. 239-257 
    Details
    ISSN: 1572-9540
    Keywords: hyperfine transitions ; deuterium ; ultra-relativistic electrons ; polarization ; atomic beam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present data showing hyperfine transitions in an atomic deuterium beam induced by the (476 MHz) radio-frequency field of a 704 MeV electron beam in a storage ring. A polarized deuterium beam, produced in an atomic beam source, was crossed with a stored electron beam and analyzed with a Breit--Rabi polarimeter. Electron-beam induced transitions were singled out by injecting different combinations of hyperfine states. Transition probabilities as high as 70% were measured at large currents (~ 100 mA). All possible deuterium transitions for a radio-frequency of 476 MHz were observed. In addition, a 1--6 transition resulting from the first harmonic (952 MHz) was observed. The effects of these transitions are of general importance for the polarized internal target technique applied in nuclear and particle physics experiments. The data are reasonably described by numerical estimates. The observed mechanism can be exploited to create nuclear polarized atoms when injecting electron polarized atoms with no net nuclear polarization into a storage cell. However, when nuclear polarized atoms are injected, care should be taken to avoid this mechanism, since it would result in depolarization of the atoms. The studies enabled us to choose the magnetic guide field during our spin-dependent electron--deuteron scattering experiments, such that electron-beam induced depolarizing effects were avoided.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012696020930
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    Universal Alignment Probabilities and Subset Selection for Ordinal Optimization (1997)
    Springer
    Journal of optimization theory and applications 93 (1997), S. 455-489 
    Details
    ISSN: 1573-2878
    Keywords: Subset selection ; stochastic optimization ; alignment probability ; ordered performance curve ; simulation ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We examine in this paper the subset selection procedure in the context of ordinal optimization introduced in Ref. 1. Major concepts including goal softening, selection subset, alignment probability, and ordered performance curve are formally introduced. A two-parameter model is devised to calculate alignment probabilities for a wide range of cases using two different selection rules: blind pick and horse race. Our major result includes the suggestion of quantifiable subset selection sizes which are universally applicable to many simulation and modeling problems, as demonstrated by the examples in this paper.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022614327007
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    Comparison of Various Techniques for Modelling Flexible Beams in Multibody Dynamics (1997)
    Springer
    Nonlinear dynamics 12 (1997), S. 367-397 
    Details
    ISSN: 1573-269X
    Keywords: Flexible ; simulation ; multibody ; dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The modelling of flexible elements in mechanical systems has been widely investigated through several methods issuing from both the area of structural mechanics and the field of multibody dynamics. As regards the latter discipline, beside the problem of the generation of the multibody equations of motion, the choice of a spatial discretization method for modelling flexible elements has always been considered as a critical phase of the modelling. Although this subject is abundantly tackled in the open-literature, the latter probably lacks an objective comparison between the most commonly used approaches. This contribution presents an extensive investigation of several discretization techniques of flexible beams, in a pure multibody context. In particular, it is shown that shape functions based on power series monomials are very suitable and versatile to model beams being part of a multibody system and thus constitutes an interesting alternative to finite element analysis. For this purpose, a symbolic multibody program, in which various discretization techniques were implemented, was generalized to compute the equations of motion of a general multibody system containing flexible beams.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008204330035
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