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  • Artikel  (31.647)
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  • 1
    Digitale Medien
    Digitale Medien
    Predictors of the peak width for networks with exponential links (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 1-16 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Width function ; instantaneous unit hydrograph ; peak ; regression ; birth-death process
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract We investigate optimal predictors of the peak (S) and distance to peak (T) of the width function of drainage networks under the assumption that the networks are topologically random with independent and exponentially distributed link lengths. Analytical results are derived using the fact that, under these assumptions, the width function is a homogeneous Markov birth-death process. In particular, exact expressions are derived for the asymptotic conditional expectations ofS andT given network magnitudeN and given mainstream lengthH. In addition, a simulation study is performed to examine various predictors ofS andT, includingN, H, and basin morphometric properties; non-asymptotic conditional expectations and variances are estimated. The best single predictor ofS isN, ofT isH, and of the scaled peak (S divided by the area under the width function) isH. Finally, expressions tested on a set of drainage basins from the state of Wyoming perform reasonably well in predictingS andT despite probable violations of the original assumptions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543424
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  • 2
    Digitale Medien
    Digitale Medien
    Technical comments (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 68-69 
    Details
    ISSN: 1436-3259
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543428
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  • 3
    Digitale Medien
    Digitale Medien
    Single station and regional analysis of daily rainfall extremes (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 281-292 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Generalised Pareto distribution ; Peaks over threshold ; Probability weighted moments ; Regionalisation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract A peaks over threshold (POT) method of analysing daily rainfall values is developed using a Poisson process of occurrences and a generalised Pareto distribution (GPD) for the exceedances. The parameters of the GPD are estimated by the method of probability weighted moments (PWM) and a method of combining the individual estimates to define a regional curve is proposed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543461
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  • 4
    Digitale Medien
    Digitale Medien
    Basinwide flood control system by combining prediction and reservoir operation (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 31-49 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Reservoir operation ; prediction ; Kalman filtering ; flood prevention ; fuzzy control
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract Japan has traditionally performed flood prevention through the construction and use of dikes, storage reservoirs, and basins which are costly and time consuming options. Another non-structural option is to operate the flood control system appropriately with a view to reducing flood damage. In this paper, a flood control system combining the runoff prediction model in the whole river basin with the reservoir operation is discussed. Different models of the runoff process are introduced in order to compare their accuracies and the computational time for the flood forecasting system. The reservoir operational rule is formulated in terms of fuzzy inference theory. Historical data are applied in a case study for verification of the proposed theories.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543426
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  • 5
    Digitale Medien
    Digitale Medien
    Reply (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 69-69 
    Details
    ISSN: 1436-3259
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543429
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  • 6
    Digitale Medien
    Digitale Medien
    Announcements (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 154-154 
    Details
    ISSN: 1436-3259
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01544078
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  • 7
    Digitale Medien
    Digitale Medien
    A survey of numerical methods for stochastic differential equations (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 155-178 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Stochastic differential equations ; Stochastic Taylor formula ; Numerical methods ; Simulations ; Strong convergence ; Weak convergence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract The development of numerical methods for stochastic differential equations has intensified over the past decade. The earliest methods were usually heuristic adaptations of deterministic methods, but were found to have limited accuracy regardless of the order of the original scheme. A stochastic counterpart of the Taylor formula now provides a framework for the systematic investigation of numerical methods for stochastic differential equations. It suggests numerical schemes, which involve multiple stochastic integrals, of higher order of convergence. We shall survey the literature on these and on the earlier schemes in this paper. Our discussion will focus on diffusion processes, but we shall also indicate the extensions needed to handle processes with jump components. In particular, we shall classify the schemes according to strong or weak convergence criteria, depending on whether the approximation of the sample paths or of the probability distribution is of main interest.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543857
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  • 8
    Digitale Medien
    Digitale Medien
    Evaluation of rainfall-runoff performance using the stochastic integral equation method (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 217-226 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Stochastic integral equation method ; rainfall-runoff models ; confidence interval
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract The stochastic integral equation method (S.I.E.M.) is used to evaluate the relative performance of a set of both calibrated and uncalibrated rainfall-runoff models with respect to prediction errors. The S.I.E.M. is also used to estimate confidence (prediction) interval values of a runoff criterion variable, given a prescribed rainfall-runoff model, and a similarity measure used to condition the storms that are utilized for model calibration purposes. Because of the increasing attention given to the issue of uncertainty in rainfall-runoff modeling estimates, the S.I.E.M. provides a promising tool for the hydrologist to consider in both research and design.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543861
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  • 9
    Digitale Medien
    Digitale Medien
    A practical method for outlier detection in autoregressive time series modelling (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 241-260 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Hat matrix ; Mahalanobis distance ; Additive outliers ; Innovation outliers ; Influential data ; Autoregressive models ; Threshold autoregression ; Lake Huron
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract A practical method is developed for outlier detection in autoregressive modelling. It has the interpretation of a Mahalanobis distance function and requires minimal additional computation once a model is fitted. It can be of use to detect both innovation outliers and additive outliers. Both simulated data and real data re used for illustration, including one data set from water resources.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543459
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  • 10
    Digitale Medien
    Digitale Medien
    A stability analysis of the geostatistical approach to aquifer transmissivity identification (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 293-316 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Confined aquifer ; Transmissivity identification ; Geostatistics ; Inverse problem ; Ill-posedness ; Ill-conditioning ; Stability analysis ; Regularization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract In recent years, geostatistical concepts have been applied to the inverse problem of transmissivity estimation from piezometric head data. It has been claimed that such methods overcome various difficulties encountered in other approaches. However, the reconstruction of transmissivity from head measurements is ill-posed as it depends on derivatives of the head field. Consequently, any accurate method for its solution is likely to encounter numerically ill-conditioned systems. This paper reviews the geostatistical approach, and uses the stability analyses of linear algebra to show that, as the amount of available data increases and the discretization of the system is refined, both a numerically ill-conditioned parameter estimation problem and ill-conditioned cokriging equations may appear. Therefore, while the geostatistical approach does have conceptual appeal, it does not avoid the fundamental difficulties arising out of the ill-posed nature of transmissivity identification. Instead, the method is likely to be quite sensitive to these difficulties, so care must be taken in its formulation to minimize their effects. A means to stabilize the geostatistical method is suggested and numerical experiments that highlight key points of our analysis are given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543462
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  • 11
    Digitale Medien
    Digitale Medien
    Offsets of curves on rational B-spline surfaces (1989)
    Springer
    Engineering with computers 5 (1989), S. 39-46 
    Details
    ISSN: 1435-5663
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau , Technik allgemein
    Notizen: Abstract The construction of offset curves is an important problem encountered often in design processes and in interrogation of geometric models. In this paper the problem of construction of offsets of curves lying on the same parametric surface is addressed. A novel algorithm is introduced, whose main feature is the use of geodesic paths to determine points of the offset. The offset is then approximated in the underlying surface parameter space by B-splines interpolating data points obtained by traveling a known distance along the geodesics departing from corresponding points of the progenitor in a direction perpendicular to the latter. A comprehensive error checking scheme has been devised allowing adaptive improvement of the approximation of the offset. The applicability of the algorithm is demonstrated by number of numerical examples.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01201996
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  • 12
    Digitale Medien
    Digitale Medien
    Factors that affect planning in a knowledge-based system for mechanical engineering design optimization with application to the design of mechanical power transmissions (1989)
    Springer
    Engineering with computers 5 (1989), S. 47-62 
    Details
    ISSN: 1435-5663
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau , Technik allgemein
    Notizen: Abstract Intelligent computer-aided design (CAD) emulates the human activity of design so that production planning, decision making, and inventive design can be performed by computers. Based on the history of human experience in engineering design, a formalized and systematic approach to design should include procedures from (1) conceptual design, (2) layout design, and (3) numerical optimization. The highest level within such a system should be responsible for specifying and symbolically optimizing skeleton structures of generic (nonspecific) elements within the design process that are eventually to be specified uniquely (pinned down) and ultimately optimized numerically. Planning plays a key role in such a system. Planning has been utilized as a tool for process organization within the knowledge domains of chemical engineering, electrical engineering, manufacturing, as well as for general problem formulation and solution. State estimation, subtask scheduling, and constraint propagation have been found to be factors of prime importance in this type of problem. Problems associated with the implementation of a planning strategy within a knowledge-based system for mechanical engineering design optimization are discussed. A hypothesis for planning is put forth and examined within the context of a model of the mechanical design optimization process. An example that demonstrates the applicability of this approach to mechanical power transmission design is considered.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01201997
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  • 13
    Digitale Medien
    Digitale Medien
    Object-oriented knowledge frameworks (1989)
    Springer
    Engineering with computers 5 (1989), S. 79-89 
    Details
    ISSN: 1435-5663
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau , Technik allgemein
    Notizen: Abstract This paper introduces a strategy for the construction of object-oriented knowledge frameworks. Global control programs, which are traditionally used for manipulating structured representations, have been replaced by domain-specific resources. This new approach offers increased efficiency and simplified development of knowledge-based expert systems for problem domains that deal with a variety of complex structured information. A theoretical foundation is laid for the representation of knowledge, starting with the adoption of a simple schema for structuring stereotypical information. Data and method abstraction is achieved by installing knowledge frames into part of an object-oriented class system that supports procedural attachment and object communication. This allows frame specialization using domain-specific resources and subsequent construction of modular systems with these specialist frames. Editors are introduced for the alteration of data primitives used in declarative representation. Algorithms, which operate on these data primitives, are given for frame instantiation, data access, and user-directed inference. Examples from structural engineering are used throughout the paper to illustrate the practical application of object-oriented knowledge frameworks.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01199071
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  • 14
    Digitale Medien
    Digitale Medien
    Improved optimum structural design by passive control (1989)
    Springer
    Engineering with computers 5 (1989), S. 13-22 
    Details
    ISSN: 1435-5663
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau , Technik allgemein
    Notizen: Abstract The problem of optimum structural design by passive control is stated in a nonlinear programming form. A solution procedure, based on a successive selection of design and control variables, is presented. Neglecting the implicit analysis equations, the solution becomes independent of the control variables and a lower bound (LB) on the optimum can easily be obtained. The control variables are then selected to satisfy all constraints. If this cannot be achieved, the LB constraints are modified and the control variables are chosen for the revised optimal design. These two steps are repeated until the final optimum is reached. Employing the proposed procedure on various structural systems subjected to static loads showed that the final optimum has been achieved after a very small number of iteration cycles. The numerical examples illustrate a solution with two types of control devices: a linear spring device and a limited displacement device. It has been found that the final optimum is often identical or close to the initial LB solution. Savings of 14 to 63 percent in weight, compared with conventional optima without control, have been demonstrated for some common structures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01201994
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  • 15
    Digitale Medien
    Digitale Medien
    An expert system for field inspection of concrete dams: Part 1, engineering knowledge (1989)
    Springer
    Engineering with computers 5 (1989), S. 23-38 
    Details
    ISSN: 1435-5663
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau , Technik allgemein
    Notizen: Abstract This paper covers in more detail the material that was introduced in Ref. [1] and describes the final engineering reasoning and knowledge used for an expert system to assist during the field inspection of existing concrete dams. The knowledge base of this expert system was created by combining the traditional expert system approach with the reasoning procedures of qualitative physics. The traditional expert system approach was used to identify the shallow knowledge pertaining to the problem, and qualitative physics was used to identify the deep knowledge. The deep knowledge structured and organized the identification and representation of the shallow knowledge. The expert system uses shallow knowledge to combine a qualitative expert reasoning with a quantitative procedural evaluation of the stability of a dam. The present paper concentrates on the description of the engineering knowledge and Ref. [2] will concentrate on the artificial intelligence issues associated with the knowledge acquisition and representation associated with this expert system. The validation process compared results obtained by the expert system with those obtained by independent field inspection experts. Some of the results are presented here.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01201995
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  • 16
    Digitale Medien
    Digitale Medien
    An expert system for setting time steps in dynamic finite element programs (1989)
    Springer
    Engineering with computers 5 (1989), S. 205-219 
    Details
    ISSN: 1435-5663
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau , Technik allgemein
    Notizen: Abstract An expert system, ETUDES—Expert Time integration control Using Deep and Surface Knowledge System, which addresses the determination of the timestep for time integration of linear structural dynamic equations is described. This time-step may also be applicable for a moderately nonlinear simulation of the same structure. The program also determines whether an explicit or implicit method is most efficient for the particular simulation. A production rule programming system written in OPS5 is used for the implementation of this prototype expert system. Issues relating to the expert system architecture for this application, such as knowledge representation and structure, as well as domain knowledge are discussed. The prototype is evaluated by measuring it's performance in various benchmark model problems.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02274213
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  • 17
    Digitale Medien
    Digitale Medien
    h andh-p version error estimation and adaptive procedures from theory to practice (1989)
    Springer
    Engineering with computers 5 (1989), S. 221-234 
    Details
    ISSN: 1435-5663
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau , Technik allgemein
    Notizen: Abstract In this paper we introduce techniques that allow us to define a posteriori error estimators via well-known recovery techniques. These allow us to construct a posteriori error estimators for relatively general problems. Further, we introduce new adaptive procedures that make use of these estimators and, in particular, describe anh-p procedure that is simple to implement and that, as numerical experiments have shown, attains an accelerated rate of convergence expected from theh-p version.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02274214
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  • 18
    Digitale Medien
    Digitale Medien
    Announcement (1989)
    Springer
    Engineering with computers 5 (1989), S. 259-259 
    Details
    ISSN: 1435-5663
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02274217
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  • 19
    Digitale Medien
    Digitale Medien
    AnO(N) algorithm to automatically generate geometric triangulations satisfying the Delaunay circumsphere criteria (1989)
    Springer
    Engineering with computers 5 (1989), S. 177-193 
    Details
    ISSN: 1435-5663
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau , Technik allgemein
    Notizen: Abstract This paper presents an algorithm for the generation of Delaunay triangulations for general nonmanifold geometric models. Octree concepts are used for point placement and providing the linear, with respect to the number of elements, growth rate of the algorithm. Compatibility and classification procedures are used in conjunction with point injection procedures to ensure that the final Delaunay triangulation is a geometric triangulation of the domain of interest.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02274211
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  • 20
    Digitale Medien
    Digitale Medien
    Automatic mesh generation for complex three-dimensional regions using a constrained Delaunay triangulation (1989)
    Springer
    Engineering with computers 5 (1989), S. 161-175 
    Details
    ISSN: 1435-5663
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau , Technik allgemein
    Notizen: Abstract This paper describes a method for generating tetrahedral meshes. The algorithm, based on the Delaunay triangulation, can treat objects of essentially arbitrary complexity. In order to preserve the surface triangulation of solid objects, it is necessary to override the Delaunay property and redefine the triangulation when points are introduced that are close to solid boundaries. Details of this constrained Delaunay algorithm are presented and an efficient implementation of the triangulation method is described. Techniques for controlling the distribution of mesh points and tetrahedron quality are also discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02274210
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  • 21
    Digitale Medien
    Digitale Medien
    Knowledge-based control for finite element analysis (1989)
    Springer
    Engineering with computers 5 (1989), S. 195-204 
    Details
    ISSN: 1435-5663
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau , Technik allgemein
    Notizen: Abstract This paper shows that control logic may be separated from analysis software and that a knowledge-based expert system can use this logic to perform interactive computation. Heuristics that control a simple interactive finite element analysis program are represented using a rule-based format and are used by a goal-driven logic processor to invoke analysis activity. Traditional algorithm-oriented control and the proposed knowledge-based control are compared in a simple displacement computation scenario to identify the advantages/disadvantages of the two approaches. General activities and constraints, practical methods of reasoning and representation, and knowledge-based expert systems are discussed with emphasis on applications to interactive finite element analysis. An analysis control expert system has been developed for use in the numerical analysis of two-dimensional linear problems in solid and structural mechanics. An example problem is used to clarify the methods used to direct activity and to identify the problems associated with conditional task processing for interactive analysis. The main difference between the analysis program described in this paper and conventional analysis programs is related to the control architecture. The general conclusion of this paper is that knowledge-based control is more effective and flexible than algorithm-oriented control.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02274212
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  • 22
    Digitale Medien
    Digitale Medien
    Adaptive multiple-levelh-refinement in automated finite element analyses (1989)
    Springer
    Engineering with computers 5 (1989), S. 235-247 
    Details
    ISSN: 1435-5663
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau , Technik allgemein
    Notizen: Abstract This paper discusses an automatic, adaptive finite element modeling system consisting of mesh generation, finite element analysis, and error estimation. The individual components interact with one another and efficiently reduce the finite element error to within an acceptable value and perform only a minimum number of finite element analyses. One of the necessary components in the automated system is a multiple-level local remeshing algorithm. Givenh-refinement information provided by an a posteriori error estimator, and adjacency information available in the mesh data structures, the local remeshing algorithm grades the refinement toward areas requesting refinement. It is shown that the optimal asymptotic convergence rate is achieved, demonstrating the effectiveness of the intelligent multiple-level localh-refinement.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02274215
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  • 23
    Digitale Medien
    Digitale Medien
    Therapeutic laser guidelines: On the effects of laser radiation on human skin-fibroblast metabolism in culture (1989)
    Springer
    Lasers in medical science 4 (1989), S. 31-40 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Summary A promising field of laser utilization is the modification of cell behaviour. Acting on cell biological functions it might be possible to use them to improve medical therapies. This possibility suggests investigation of dosimetry guidelines employing different wavelenghts, power and exposure durations for future potential use of lasers in medicine. In this line of investigation, structural organization and viability of fibroblast has been studied, thus observing that the cell number remains unaltered by low density laser irradiation. Nevertheless, results observed in metabolism variation suggest that, with appropiate irradiation-protocol an efficient modality for enhancement or modulation of cell activity can be found, and thereafter used for therapeutical pourposes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276668
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  • 24
    Digitale Medien
    Digitale Medien
    Experimental effects of Argon and CO2 lasers on skin and vessels (1989)
    Springer
    Lasers in medical science 4 (1989), S. 95-103 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Summary Response of rabbit ear blood vessels and defects on the pig skin to Argon and CO2 lasers, (1 to 4 Watts and 0,1 to 0,2 sec pulses), were analysed. Examining lesion depth and its diameter, it was seen, using both lasers, that when power and time exposure increased, lesion depth increased as well, At the same time, when power was increased and the time of irradiation was constant, the diameter of the lesion remained approximately the same. Histologically, by using Argon laser at 1'5 W, there is no evidence of skin lesion but vessel coagulation occurs. On the other hand, more power (3 to 4 W) produces skin destruction. CO2 laser at 1'5 W causes skin destruction while 3 W penetrates deeper, cutting all tissues and producing vessel-wall fragmentation and haemorrhage. In contrast to CO2 laser, which definitly stops blood circulation by cutting the vessels, Argon laser entails many recurrences and vessels re-start circulation; a fact which is not desirable in cutaneous vascular disorders treatment.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276673
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  • 25
    Digitale Medien
    Digitale Medien
    The present state of safety laws and regulations in the FRG (1989)
    Springer
    Lasers in medical science 4 (1989), S. 213-213 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276688
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  • 26
    Digitale Medien
    Digitale Medien
    Title: Development of national safety regulations for medical use of lasers in the Netherlands (1989)
    Springer
    Lasers in medical science 4 (1989), S. 235-238 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract Until now there are no national safety regulations for the medical use of lasers in the Netherlands. However, a committee of experts from hospitals, Health Council of the Netherlands, TNO Medical Technology Unit and industry is preparing recommendations. Their work is based on MPE values and special measurements that are performed to assess divergence and intensity distribution of laser beams, as well as optical and thermal properties of materials that are used in the clinical setting. The final intention of the committee is to advise government and hospitals on technical, environmental and administrative measures for the safety of the various medical laser applications.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276691
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  • 27
    Digitale Medien
    Digitale Medien
    The accident prevention regulation “Laser Radiation” (VGB 93) — Special regulations for the safe use of laser products in the Federal Republic of Germany (1989)
    Springer
    Lasers in medical science 4 (1989), S. 243-249 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract Accident prevention regulations, e.g. VBG 93 “Laser Radiation”, are a national particularity in the FRG. The regulations issued by the injuries insurance institutes are binding upon employers and employees. The apparatus and equipment safety law makes the VBG 93 obligatory also for manufacturers and importers. National and international standards are referred to in relevant context in the VBG 93. The VBG 93 is also used by the governmental authorities for the protection of labour. The medical apparatus decree has to be observed also for medical application. Some important aspects of the VBG 93 will be described in detail.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276693
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  • 28
    Digitale Medien
    Digitale Medien
    Proposal for dosimetry of non-ionizing radiation (1989)
    Springer
    Lasers in medical science 4 (1989), S. 329-340 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract In general “Dose” by itself as an amount of energy is not a relevant parameter for the description of penetration by non-ionizing (laser) radiation. But dosimetry should not only include the measurements of relevant parameters and its relatioships to tissue effects but also include all possibilities of measurements and relationships which help to control the biological result on tissue by irraditation with non-ionizing laser radiation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276699
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  • 29
    Digitale Medien
    Digitale Medien
    Laser therapeutic guidelines used in the Lisbon Institute of Ophthalmology (1989)
    Springer
    Lasers in medical science 4 (1989), S. 361-365 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract In this paper the Author presents the guidelines of laser therapy in the Lisbon Institute of Ophthalmology, with spetial referance to the laser parameters, the ocular pathology imposing laser therapy and the necessary conditions for safety of the patient and of the doctor, operating with laser.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276703
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  • 30
    Digitale Medien
    Digitale Medien
    Study of laser-tissue interactions through Raman spectroscopy (1989)
    Springer
    Lasers in medical science 4 (1989), S. 41-61 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract A review is presented of Raman spectroscopic applications in the study of laser-tissue interactions. The basic definitions of Raman spectroscopy are given with emphasis to those concepts and techniques which are relevant to biomedical material characterization. Representative problems from current literature will be discussed, like atherosclerosis of human vessels, eye lens aging, formation and diagnosis of cataracts.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276669
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  • 31
    Digitale Medien
    Digitale Medien
    Comparison of lasers for photodynamic therapy with a phthalocyanine photosensitizer (1989)
    Springer
    Lasers in medical science 4 (1989), S. 7-12 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract Three different lasers were compared under the same conditions for their effectiveness at producing photodynamic damage to normal colon following sensitization with aluminium sulphonated phthalocyanine (AlSPc). One laser was an argon ion pumped continuous wave (CW) dye laser and the other two were pulsed at 10 kHz (copper vapour laser pumped dye laser, and 5 Hz (flashlamp pumped dye laser). The CW and 10 kHz laser were equally effective at producing damage. The 5 Hz laser failed to produce a photodynamic effect, although occasionally caused a photomechanical effect when the laser fibre was placed touching the colonic mucosa. Quantitative analysis suggests that the high energy pulses of the flashlamp pumped dye laser saturate AlSPc, so very little of the available energy can be used to produce a photodynamic effect, in contrast to the two other lasers which do not produce saturation conditions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032503
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  • 32
    Digitale Medien
    Digitale Medien
    Effect of the non-contact mode of YAG laser on pulmonary tissues and its comparison with electrodiathermy: An anatomo-pathological study (1989)
    Springer
    Lasers in medical science 4 (1989), S. 17-23 
    Details
    ISSN: 1435-604X
    Schlagwort(e): YAG Laser/Electrodiathermy ; Pulmonary tissue
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract An anatomo-pathological study was undertaken to evaluate the early effects of high and low powered non-contact mode of YAG laser on pulmonary tissue and to compare these effects with those resulting from electro-diathermy. In 40 patients with bronchial carcinoma, thoracotomy was carried out using conventional surgical methods, the part of the lung destined to be excised was then exposed to: Non-contact YAG laser of high or low power (Group A, n=15); cutting/ or coagulation electro-diathermy (Group B,n=15); and mixed (blend) cutting and coagulation electro-diathermy (Group C,n=10). The results indicated that high power non-contact YAG laser is capable of incising the pulmonary parenchyma without bleeding or air leak, only the larger and sub-segmental vessels and bronchial branches needed suturing. This was not the case for electro-diathermy, either in its cutting or blend form. The low power laser was capable of sealing off the superficial bleeding vessels and contracting the alveolar sacs, thus preventing bleeding and air leak. Only the superficial bleeding could be stopped by coagulation diathermy which had no effect in preventing air leak from the parenchyma. Microscopically, apart from evaporation, laser produced charring and coagulative necrosis in the remaining exposed tissue. No evaporation of tissue occurred with electro-diathermy (either in its cutting, blend or coagulation mode). Only a very limited charring and coagulative necrosis was present in the remaining tissues exposed to coagulation electro-diathermy.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032505
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  • 33
    Digitale Medien
    Digitale Medien
    Open lung surgery with Nd-YAG Laser (1989)
    Springer
    Lasers in medical science 4 (1989), S. 13-16 
    Details
    ISSN: 1435-604X
    Schlagwort(e): Nd-YAG laser ; Open lung surgery
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract We report on nineteen patients who successfully underwent open lung performance with a Nd-YAG laser in the period December 1987 to August 1988. Reasons for laser operations were lung metastases (twelve cases), lung fibrosis (five patients), one lung cyst and one tuberculoma. We used the Nd-YAG laser in non-contact mode, with focus hand-piece spot size of 1.5 mm, a continual 1064 nm wavelength and a power output 90 W. In these nineteen cases we performed 35 laser photoablations of lung tissue. All patients healed without any serious complications. The major advantage of Nd-YAG laser beam in open lung surgery is in the rapid sealing effect of small airways and of blood vessels up to 3 mm. The Nd-YAG laser seems to be very suitable for operations in lung periphery.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032504
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  • 34
    Digitale Medien
    Digitale Medien
    Book reviews (1989)
    Springer
    Lasers in medical science 4 (1989), S. 65-65 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032510
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  • 35
    Digitale Medien
    Digitale Medien
    Meetings announcements (1989)
    Springer
    Lasers in medical science 4 (1989), S. 71-72 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032512
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  • 36
    Digitale Medien
    Digitale Medien
    Photodynamic treatment of cholesteatoma of the ear induced experimentally in rabbits: Preliminary report (1989)
    Springer
    Lasers in medical science 4 (1989), S. 111-113 
    Details
    ISSN: 1435-604X
    Schlagwort(e): Cholesteatoma ; Haematoporphyrin ; Photo-dynamic therapy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract In a previous project on haematoporphyrin (HP) uptake by experimentally induced cholesteatoma of the rabbit, it was shown that HP concentration was remarkably high in the cholesteatoma, with a peak at three hours after intravenous administration of the drug. On the basis of these results an attempt was made to destroy the matrix of cholesteatoma by means of photodynamic therapy. Cholesteatomas were induced bilaterally in the ears of eight rabbits which were divided into two groups, according to the interval between HP administration (5 mg/kg body weight) and irradiation. The irradiation was carried out with light at 600–680 nm, filtered from the emission a quartz halogen lamp (dose rate 300 mW cm−2; total dose 120 J cm−2). The first group was submitted to photodynamic therapy after three hours and the second after twelve hours. In both groups half the rabbits were sacrificed at 24 h and half at 48 h post-irradiation. Histological studies showed significant vascular lesions, necrosis of the wall of the cholesteatoma, interstitial extravasation of blood, and oedema in a high percentage of the animals. The lesions were much greater in animals sacrificed at 48 h after photodynamic therapy.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032607
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  • 37
    Digitale Medien
    Digitale Medien
    Meetings announcements (1989)
    Springer
    Lasers in medical science 4 (1989), S. 137-138 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032612
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  • 38
    Digitale Medien
    Digitale Medien
    The role of the CO2 laser in out-patient oral surgery (1989)
    Springer
    Lasers in medical science 4 (1989), S. 151-154 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract The treatments of 250 patients with the CO2 laser is described. The procedures were performed under local anaesthesia with minimal instrumentation apart from the laser. Operations were rapid and relatively bloodless, and excellent cosmetic and functional results were obtained. In the post-operative period there was minimal oedema and no significant bleeding. Post-operative pain was also minimal allowing patients to resume their normal diet on the first post-operative day and to return to work. The experience gained with this first group of patients suggests that ideal cases for treatment by this modality include leukoplakia, haemangiomas, epulis and prosthesis fibromas. The CO2 laser is now being used to a lesser extent on in-patients and on those with malignant lesions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032428
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  • 39
    Digitale Medien
    Digitale Medien
    Laser-induced fluorescence used in localizing atherosclerotic lesions (1989)
    Springer
    Lasers in medical science 4 (1989), S. 171-181 
    Details
    ISSN: 1435-604X
    Schlagwort(e): Autofluorescence ; Laser-induced fluorescence ; Laser-induced breakdown spectroscopy ; Atherosclerosis ; Tissue diagnostics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract We have investigated laser-induced fluorescence frompost mortem human arteries in order to find spectroscopic properties allowing discrimination between normal and atherosclerotic vessel wall. A pulsed nitrogen laser emitting light at a wavelength of 337.1 nm was used as an excitation source. The fluorescence spectrum from 370 to 700 nm was captured and analysed by an optical multichannel analyser. Dimensionless contrast functions were formed by using characteristic spectral features at 390, 415, 480, 580 and 600 nm. All samples were investigated in scans across a region where normal as well as diseased vessel wall appeared. The types of plaque were histopathologically divided into four groups, of which three could be singled out using one or more of our spectroscopic criteria. We also investigated the different layers of the normal and diseased vessel wall in order to determine the various contributions to the fluorescence signal. Furthermore, plasma emission spectra were recorded while ablating the normal as well as the diseased vessel wall with an excimer laser, emitting radiation at 308 nm, thus detecting the change in spectral characteristics during the ablation process down into deeper layers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032432
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  • 40
    Digitale Medien
    Digitale Medien
    Meetings announcements (1989)
    Springer
    Lasers in medical science 4 (1989), S. 203-204 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032438
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  • 41
    Digitale Medien
    Digitale Medien
    Photodynamic therapy for the treatment of advanced gastrointestinal tumours (1989)
    Springer
    Lasers in medical science 4 (1989), S. 183-186 
    Details
    ISSN: 1435-604X
    Schlagwort(e): Photodynamic therapy ; Gastrointestinal tumour ; Advanced lesions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract In the study, 120 patients with advanced gastrointestinal tumours were treated by PDT; 5 mg/kg of HpD was intravenously given 48–72 h prior to PDT. The light source was an argon dye laser with an output beam of 630 nm. The irradiation time varied from 15–25 min with a power of 100–350 mW cm−2. The entire tumour was irradiated with a light dose of 100–250 J cm−2. Of the 120 patients, 20 had cancer of esophagus, 72 had cancer of the gastric cardia, 18 had cancer of the stomach and 10 had cancer of the rectum. Eighty-eight patients (73.3%) had a response to PDT. Twelve patients with CR were followed up for one to five years, two patients died during the two years after PDT.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032433
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  • 42
    Digitale Medien
    Digitale Medien
    Identification of brain tumours in rats using laser-induced fluorescence and haematoporphyrin derivative (1989)
    Springer
    Lasers in medical science 4 (1989), S. 241-249 
    Details
    ISSN: 1435-604X
    Schlagwort(e): Brain tumour ; Rat ; Detection ; Fluorescence ; Laser ; Haematoporphyrin derivative
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract Laser-induced fluorescence has been used for the identification of brain tumours in rats, which have been previously given tumour-seeking haematoporphyrin derivative. A pulsed nitrogen laser (λ=337 nm) was used in conjunction with an optical multichannel analyzer. For both inoculated RG-2 and TCVC rat-brain-tumour models, the blue autofluorescence was strongly reduced in the tumour compared with normal brain tissue, and at the same time the characteristic red-drug signal increased. The contrast between tumour and normal tissue was strongly enhanced by forming the ratio between the two signals. Implications for possible improvement of tumour delineation in brain tumour surgery are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032454
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  • 43
    Digitale Medien
    Digitale Medien
    New laser literature (1989)
    Springer
    Lasers in medical science 4 (1989), S. 285-287 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032461
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  • 44
    Digitale Medien
    Digitale Medien
    A single transcutaneous light irradiation to injured peripheral nerve: Comparative study with five different wavelengths (1989)
    Springer
    Lasers in medical science 4 (1989), S. 259-263 
    Details
    ISSN: 1435-604X
    Schlagwort(e): Low-level laser irradiation ; Peripheral nerve injury ; Single effect of 632.8, 660, 830, 880 and 950 nm wavelengths
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract Twenty rats underwent a crush injury to their sciatic nerve, followed immediately by a single low-power coherent or non-coherent irradiation administered transcutaneously on the projection of an injured peripheral nerve. Five wavelengths were tested: 632.8, 660, 830, 880 and 950 nm. The electrical activities of the crushed nerve, immediately after irradiation and on the following first, third and seventh day post-crush, were compared to the precrush activity. The results indicate that energy at the wavelength of 632.8 nm (CW He-Ne laser), delivered transcutaneously (10 J cm−2 at each point) along the projections of the nerve, prevents the drop in the functional nerve activity as measured by the combined action potential (AP) after crush injury. Other wavelengths were either less effective (660 nm) or totally ineffective under the same conditions. The beneficial effects were temporary and lasted only one day after injury and the single irradiation session.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032456
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  • 45
    Digitale Medien
    Digitale Medien
    New laser literature (1989)
    Springer
    Lasers in medical science 4 (1989), S. 199-202 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032437
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  • 46
    Digitale Medien
    Digitale Medien
    Report on the photodynamic therapy dosimetry meeting: April 1989 (1989)
    Springer
    Lasers in medical science 4 (1989), S. 211-220 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032450
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  • 47
    Digitale Medien
    Digitale Medien
    Argon laser therapy of port-wine stains—Prediction of the effect by transcutaneous microscopy (1989)
    Springer
    Lasers in medical science 4 (1989), S. 237-240 
    Details
    ISSN: 1435-604X
    Schlagwort(e): Argon laser ; Port-wine stains ; Transcutaneous microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract Sixty-two consecutive patients presenting with facial port-wine stains were examined by transcutaneous microscopy prior to argon laser treatment. The capillary morphology was classified and the late outcome was independently examined and scored. It was found that capillary appearances do have some value in predicting a favourable response and in predicting scarring.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032453
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  • 48
    Digitale Medien
    Digitale Medien
    Argon laser treatment of solid Ehrlich carcinoma tumours sensitized with some porphyrin compounds (1989)
    Springer
    Lasers in medical science 4 (1989), S. 265-268 
    Details
    ISSN: 1435-604X
    Schlagwort(e): Argon laser, Photodynamic therapy ; Cancer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract The effect of continuous-wave argon laser radiation on the growth of solid Ehrlich carcinoma was studied in mice. To enhance the tumour sensitivity to laser radiation, compounds of a porphyrin series were given to animals prior to the laser treatment. Out of 14 substances tested, tetraphenylporphyn-sulphonate and its palladium complex had the most pronounced photosensitizing activity comparable with that of haematoporphyrin derivative (HPD). Metallic complexes of tetraphenylporphyn and protoporphyrin were less active. It is concluded that porphyrins are promising sensitizers for photodynamic therapy (PDT).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032457
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  • 49
    Digitale Medien
    Digitale Medien
    Meetings announcements (1989)
    Springer
    Lasers in medical science 4 (1989), S. 289-290 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032462
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  • 50
    Digitale Medien
    Digitale Medien
    Photodynamic therapy in the treatment of malignant tumours of the upper aerodigestive tract (1989)
    Springer
    Lasers in medical science 4 (1989), S. 279-284 
    Details
    ISSN: 1435-604X
    Schlagwort(e): Photodynamic therapy ; Haematoporphyrin ; Argon dye laser ; Early stage esophageal cancer ; Head and neck cancer ; Squamous cell carcinoma ; Adenocarcinoma
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract This is the report of a pilot study in which the technique of photodynamic therapy (PDT)—in which malignant tissues are destroyed by light after being previously photosensitized by haematoporphyrin or its derivative—was performed using a high power argon-dye laser system which operated at 630±5 nm and optical fibres with either a microlens or a diffusing tip. A total of thirty-seven patients were utilized for this study, including twenty-five patients affected by esophageal carcinoma, five by recurrences of head and neck cancer, four by gastric cancer and three by lung cancer. Among the sixteen cases with superficial or localized cancer of the esophagus, complete and partial responses were observed in seven and six patients, respectively. In advanced and recurring cancers less satisfactory results were obtained. Thus, PDT seems to be useful in cases of small superficial cancers, either primary or recurrent after previous treatments.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032460
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  • 51
    Digitale Medien
    Digitale Medien
    Product data models (1989)
    Springer
    Research in engineering design 1 (1989), S. 43-50 
    Details
    ISSN: 1435-6066
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Technik allgemein
    Notizen: Abstract Product data models can be viewed as a class of semantic data models which take into account the needs of engineering data. In this paper the characteristics for semantic data models defined by Peckham and Maryanski [8] are taken as a starting point. The relevance of these characteristics to product data is shown. The capabilities of a prototype product description system are described in relation to the same characteristics. Additional data modeling characteristics such as parametrization and data sharing, which have been introduced to support engineering design, are then described. These can be viewed as extending beyond the accepted capabilities of semantic data models.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01580002
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  • 52
    Digitale Medien
    Digitale Medien
    A review of research in mechanical engineering design. Part I: Descriptive, prescriptive, and computer-based models of design processes (1989)
    Springer
    Research in engineering design 1 (1989), S. 51-67 
    Details
    ISSN: 1435-6066
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Technik allgemein
    Notizen: Abstract This is the first of a two part paper summarizing and reviewing research in mechanical engineering design theory and methodology. Part I includes: 1) descriptive models; 2) prescrptive models; and 3) computer-based models of design processes. Part II, which will appear in the next issue of this journal, will include: 4) languages, representations, and environments for design; 5) analysis in support of design; and 6) design for manufacture and the life-cycle. For each major area, we discuss the current topics of research and the state of the art, emphasizing recent significant advances. We also discuss the important open research issues in each area. The six categories are certainly not mutually exclusive nor even collectively exhaustive; however, some organization is necessary, and these categories have been effective in making sense of a body of research that is expending rapidly in many exciting and promising directions. The mechanical engineering design research community has made major advances over the last few years. The research community in mechanical engineering design has made significant progress not only in advancing our knowledge of design, but also in clarifying the research methods necessary to study design. Great progress is being made toward a better understanding of design, and hence toward better design tools.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01580003
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  • 53
    Digitale Medien
    Digitale Medien
    Synthesis of schematic descriptions in mechanical design (1989)
    Springer
    Research in engineering design 1 (1989), S. 3-18 
    Details
    ISSN: 1435-6066
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Technik allgemein
    Notizen: Abstract This article describes a schematic synthesis problem and one of its solution techniques. The problem domain consists of devices that can be described as networks of lumped-parameter, idealized elements in the translational-mechanical, rotational-mechanical, fluidmechanical, and electrical media. Such devices include speedometers, accelerometers, pneumatic cylinders, and pressure gauges. Design problems in this domain are specified by an input quantity, an output quantity, and the desired relationship between the input and output. The solution technique is based on three steps: 1) generate a candidate design, 2) derive and classify the behavior of the candidate, 3) based on the derived behavior and domain knowledge, modify the candidate (if possible) to bring it in line with the specification. The key idea behind this techniques is that an abstract characterization of the essential properties of the candidate design expedites the analysis and modification. The results of this work are aimed at computer tools for preliminary mechanical design.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01579999
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  • 54
    Digitale Medien
    Digitale Medien
    Fitting a stochastic partial differential equation to aquifer data (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 85-96 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Stochastic equations ; irregularly spaced observations ; prediction, interpolation ; random fields
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract The steady state two dimensional groundwater flow equation with constant transmissivities was studied by Whittle in 1954 as a stochastic Laplace equation. He showed that the correlation function consisted of a modified Bessel function of the second kind, order 1, multiplied by its argument. This paper uses this pioneering work of Whittle to fit an aquifer head field to unequally spaced observations by maximum likelihood. Observational error is also included in the model. Both the isotropic and anisotropic cases are considered. The fitted field is then calculated on a two dimensional grid together with its standard deviation. The method is closely related to the use of two-dimensional splines for fitting surfaces to irregularly spaced observations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01544074
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  • 55
    Digitale Medien
    Digitale Medien
    Stochastic analysis of estuarine hydraulics (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 71-84 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Hydraulics ; quasilinearization ; simulation ; stochastic ; estuarine system ; Monte Carlo methods ; random differential equations ; parameter uncertainty
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract A new methodology is presented for the solution of the stochastic hydraulic equations characterizing steady, one-dimensional estuarine flow. The methodology is predicated on quasi-linearization, perturbation methods, and the finite difference approximation of the stochastic differential operators. Assuming Manning's roughness coefficient is the principal source of uncertainty in the model, stochastic equations are presented for the water depths and flow rates in the estuarine system. Moment equations are developed for the mean and variance of the water depths. The moment equations are compared with the results of Monte Carlo simulation experiments. The results confirm that for any spatial location in the estuary that (1) as the uncertainty in the channel roughness increases, the uncertainty in mean depth increases, and (2) the predicted mean depth will decrease with increasing uncertainty in Manning'sn. The quasi-analytical approach requires significantly less computer time than Monte Carlo simulations and provides explicit
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01544073
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  • 56
    Digitale Medien
    Digitale Medien
    Stochastic partial differential equations in groundwater hydrology (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 135-153 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Stochastic partial differential equations ; maximum likelihood estimation ; parameter estimation ; moment equations ; stodhastic contaminant transport
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract Many problems in hydraulics and hydrology are described by linear, time dependent partial differential equations, linearity being, of course, an assumption based on necessity. Solutions to such equations have been obtained in the past based purely on deterministic consideration. The derivation of such a solution requires that the initial conditions, the boundary conditions, and the parameters contained within the equations be stipulated in exact terms. It is obvious that the solution so derived is a function of these specified, values. There are at least four ways in which randomness enters the problem. i) the random initial value problem; ii) the random boundary value problem; iii) the random forcing problem when the non-homogeneous part becomes random and iv) the random parameter problem. Such randomness is inherent in the environment surrounding the system, the environment being endowed with a large number of degrees of freedom. This paper considers the problem of groundwater flow in a phreatic aquifer fed by rainfall. The goveming equations are linear second order partial differential equations. Explicit form solutions to this randomly forced equation have been derived in well defined regular boundaries. The paper also provides a derivation of low order moment equations. It contains a discussion on the parameter estimation problem for stochastic partial differential equations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01544077
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  • 57
    Digitale Medien
    Digitale Medien
    Some results comparing Monte Carlo simulation and first order Taylor series approximation for steady groundwater flow (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 179-190 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Groundwater ; Stochastic ; Monte Carlo simulation ; First order Taylor series approximation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract The expected head and standard deviation of the head from the first order Taylor series approximation is compared to Monte Carlo simulation, for steady flow in a confined aquifer with transmissivity as a random variable. Emphasis is on the effect of changes in the covariance structure of the transmissivity, and pumping rates, on the errors in the first order Taylor series approximation. The accuracy of the first order Taylor series approximation is found to be particularly sensitive to pumping rates. With significant pumping the approximation is found to under estimate both the expected drawdown and head variance, and the error increases as the pumping rate increases. This can lead to large errors in probability constraints based on moments from the first order Taylor series approximation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543858
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  • 58
    Digitale Medien
    Digitale Medien
    Kalman filter estimation for periodic autoregressive-moving average models (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 227-240 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Kalman filter ; Maximum likelihood estimation ; Periodic models ; Stochastic hydrology ; Time series analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract An exact maximum likelihood procedure is presented for estimating the parameters of a periodic autogressive-moving average (PARMA) model. To develop an estimator which is both statistically and computationally efficient, the PARMA class of models is written using a state-space representation and a Kalman filtering algorithm is used to estimate the parameters. In order to demonstrate how to fit PARMA models in practice, the most appropriate types of PARMA models are identified for fitting to two average monthly riverflow time series and the new estimator is employed for estimating the model parameters.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543862
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  • 59
    Digitale Medien
    Digitale Medien
    An application of Karmarkar's interior-point linear programming algorithm for multi-reservoir operations optimization (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 17-29 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Stochastic optimization ; linear programming ; simplex method ; Karmarkar's method
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract Optimization of multi-reservoir systems operations is typically a very large scale optimization problem. The following are the three types of optimization problems solved using linear programming (LP): (i) deterministic optimization for multiple periods involving fine stage intervals, for example, from an hour to a week (ii) implicit stochastic optimization using multiple years of inflow data, and (iii) explicit stochastic optimization using probability distributions of inflow data. Until recently, the revised simplex method has been the most efficient solution method available for solving large scale LP problems. In this paper, we show that an implementation of the Karmarkar's interior-point LP algorithm with a newly developed stopping criterion solves optimization problems of large multi-reservoir operations more efficiently than the simplex method. For example, using a Micro VAX II minicomputer, a 40 year, monthly stage, two-reservoir system optimization problem is solved 7.8 times faster than the advanced simplex code in MINOS 5.0. The advantage of this method is expected to be greater as the size of the problem grows from two reservoirs to multiples of reservoirs. This paper presents the details of the implementation and testing and in addition, some other features of the Karmarkar's algorithm which makes it a valuable optimization tool are illuminated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543425
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  • 60
    Digitale Medien
    Digitale Medien
    Spatial rainfall estimation by linear and non-linear co-kriging of radar-rainfall and raingage data (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 51-67 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Spatial rainfall estimation ; kriging ; ordinary co-kriging ; disjunctive co-kriging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract The feasibility of linear and nonlinear geostatistical estimation techniques for optimal merging of rainfall data from raingage and radar observations is investigated in this study by use of controlled numerical experiments. Synthetic radar and raingage data are generated with their hypothetical error structures that explicitly account for sampling characteristics of the two sensors. Numerically simulated rainfall fields considered to be ground-truth fields on 4×4 km grids are used in the generation of radar and raingage observations. Ground-truth rainfall fields consist of generated rainfall fields with various climatic characteristics that preserve the space-time covariance function of rainfall events in extratropical cyclonic storms. Optimal mean areal precipitation estimates are obtained based on the minimum variance, unbiased property of kriging techniques under the second order homogeneity assumption of rainfall fields. The evaluation of estimated rainfall fields is done based on the refinement of spatial predictability over what would be provided from each sensor individually. Attention is mainly given to removal of measurement error and bias that are synthetically introduced to radar measurements. The influence of raingage network density on estimated rainfall fields is also examined.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543427
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  • 61
    Digitale Medien
    Digitale Medien
    Parameter estimation in low order fractionally differenced ARMA processes (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 97-110 
    Details
    ISSN: 1436-3259
    Schlagwort(e): ARMA processes ; fractionally differencedARMA processes ; long memory ; spectral density ; maximum likelihood estimates
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract A class of regression type estimators of the parameterd in a fractionally differencedARMA (p, q) process is introduced. This class is an extension of the estimator considered by Geweke and Porter-Hudak. In a simulation study, we compared three estimators from this class together with two approximate maximum likelihood estimators which are based on two separate approximations to the likelihood. One approximation ignores the determinant term in the likelihood and the other includes a compensating factor for the determinant. When the determinant term is included, the estimate tends to be much less biased and is in general superior to the other estimate. The approximate maximum likelihood estimator out performed, by a large margin, the regression type estimators for pureARIMA (0,d,0) processes. However, forARIMA (1,d,1) processes, a regression type estimator turned out to be the best for realizations of length 400 in 3 out of the 5 cases we tried.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01544075
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  • 62
    Digitale Medien
    Digitale Medien
    Basin-scale relations via conditioning (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 111-133 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Rainfall-runoff models ; random channel network ; regionalization ; flood frequency ; instanteous unit hydrograph
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract A rainfall-runoff model is used in conjunction with a probabilistic description of the input to this model to obtain simple regression-like relations for basin runoff in terms of basin and storm characteristics. These relations, similar to those sought in regionalization studies, are computed by evaluating the conditional distribution of model output given basin and storm characteristics. This method of conditioning provides a general way of examining model sensitivity to various components of model input. The resulting relations may be expected to resemble corresponding relations obtained by regionalization using actual runoff to the extent that the rainfall-runoff model and the model input specification are physically realistic. The probabilistic description of model input is an extension of so-called “random-model” of channel networks and involves postulating an ensemble of basins and associated probability distributions that mimic the variability of basin characteristics seen in nature. Application is made to small basins in the State of Wyoming. Parameters of the input variable distribution are estimated using data from Wyoming, and basin-scale relations are estimated both, parametrically and nonparametrically using model-generated runoff from simulated basins. Resulting basin-scale relations involving annual flood quantiles are in reasonable agreement with those presented in a previous regionalization study, but error estimates are smaller than those in the previous study, an artifact of the simplicity of the rainfall-runoff model used in this paper. We also obtain relations for peak of the instantaneous unit hydrograph which agree fairly well with theoretical relations given in the literature. Finally, we explore the issues of sensitivity of basin-scale, relations and error estimates to parameterization of the model input probability distribution and of how this sensitivity is related to making inferences about a particular ungaged basin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01544076
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  • 63
    Digitale Medien
    Digitale Medien
    A cross entropy method for flood frequency analysis (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 191-202 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Random variable ; Distribution ; Estimation ; Probability analysis ; Cross-entropy ; Fractile constraints ; Flood
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract The cross-entropy method with fractile constraints has been developed to estimate a random variable when the data are a set of independent observations of the variable. The method can claim several advantages over existing methods. It uses a reference distribution like the prior distribution in Bayesian analysis and likewise generates a posterior distribution. The method is of interest, in particular, because it satisfies two fundamental requirements for selfconsistency in the analysis of a probabilistic system based on data: a principle of invariance and a principle of data monotonicity. The method is applied to flood analysis. Robustness of the minimum cross-entropy method is compared with other methods: the methods of moments and the maximum likehood.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543859
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  • 64
    Digitale Medien
    Digitale Medien
    Estimation of flow enhancement in the Kinneret watershed due to cloud seeding (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 203-216 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Cloud seeding ; Rainfall enhancement ; Regression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract A comparison is carried out between historical records of the flow measured in Kinneret watershed during and prior to the time of cloud seeding for rainfall enhancement. Precipitation series for the control area of the meteorological experimentation serve as a reference for the comparison. The fluctuations of the flow, which would have occurred unless the effect of the seeding, are estimated by a linear regression on the precipitation as the control. The regression parameters are calibrated separately for the unseeded and for the seeded time series. The model with the parameters calibrated for the unseeded series is applied on the rainfall recorded during the seeded time, and vice versa. The difference between the measured and the computed data is attributed to the effect of cloud seeding. Similar comparisons are carried out with respect to rainfall series recorded at the target area and at the edge of the enhanced area. The results indicate that the flow from the affected sector of the watershed has been enhanced, with respect to the control, by 31×106 m 3/year, at a significance level of 31. This enhancement is 5% of the volume which is generated in that area. The rates found with respect to the rainfall at the edge are higher than those found with respect to the control, while those with respect to the rainfall at the center of the target area are lower.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543860
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  • 65
    Digitale Medien
    Digitale Medien
    A radar-based stochastic model for the time-space arrivals of the rain fields onto a geographical region (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 261-280 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Rain fields ; time-space arrivals ; stochastic model
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract Rainfall in time at any ground location can be described by the rain intensity distribution over the subtrajectories which are drawn by the ground location point on the radar-detected incremental rain fields (IRFs) that pass over this location. Based on this conceptualization, this study develops a stochastic description of the arrivals of IRF subtrajectories (SIRFs) onto any given set of ground locations over a geographical region. The arrivals of SIRFs is described by a multivariate doubly stochastic Poisson process, excited by the time-space arrival process of IRFs onto the designated geographical region. The arrival process of IRFs is described by a 3-level time-space nonhomogeneous Poisson cluster model. At the primary level of this model are the arrivals of synoptic cyclonic systems; at the secondary level are the arrivals of large mesoscale rain areas (LMSAs) and at the tertiary level are the arrivals of IRFs onto the designated geographical region, all detected by the weather radar. The models are substantiated both by the graphical analysis of rain fields, as detected on a radar scope, and by the statistical analysis of the arrivals data at all of the four levels at three different ground locations over a rectangular geographical region in Northern Kentucky. It is pointed out that a doubly stochastic Poisson process is basically a Poisson cluster process. Hence, the final process of SIRF arrivals onto any ground location may be interpreted as a 4-level Poisson cluster process. Finally, heavy tails in the sample covariance density functions of the IRF and SIRF arrivals are detected. This study shows that the appropriate incorporation of clustering at all observable distinct scales of the rain fields models the heavy tail behavior of the covariance density adequately.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543460
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  • 66
    Digitale Medien
    Digitale Medien
    CO2 lasers thermal changes on laryngeal tissue after different application modes (1989)
    Springer
    Lasers in medical science 4 (1989), S. 83-89 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Summary Standardized operations including incisions and ablations were carried out on pigthroats immediately prior to evaluation of the depths of thermal damage zones measured with a unit of 30 mikrons. The following parameters were applied on the tissue: 1) Continuous versus single pulse mode. 2) equal energy impacts with variation of time and power density. 3) super pulse versus non super pulse. In the 1st series the tissue damage for all tissues examined were significantly lower in the single pulse mode than in the continuous mode. In the 2nd series the pooled material showed a significance in favour of short impacts with high power density although the total energy required for a single operation was up to 40% higher in the high power/short time series. The 3rd series showed no significance in differences between super pulse and nonsuper pulse damage when applying the same average output on the laryngeal tissues involved.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276671
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  • 67
    Digitale Medien
    Digitale Medien
    Requirements of an up to date fibre optics delivery system for laser medicine (1989)
    Springer
    Lasers in medical science 4 (1989), S. 105-109 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract The possibility of the potential as well as the safety of an optical fibre delivery system for laser medical applications is reviewed. Fibre directional couplers and connectors are suggested to be developed in view of this power laser application. Finally a special fibre probe radiating a corolla shaped beam for laser angioplasty is briefly described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276674
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  • 68
    Digitale Medien
    Digitale Medien
    Sapphire and metal tip recanalisation: Implications for safety (1989)
    Springer
    Lasers in medical science 4 (1989), S. 119-127 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract The characteristics of two modified fiber tips, the metal laser probe and the rounded sapphire contact probe, were examined in vitro and in vivo with respect to some of the risks of laser angioplasty. Both probes have an atraumatic, blunt shape. The laser beam profile of the sapphire contact probe looses its focussing properties in water. In vitro, we found a large temperature gradient from the front to the rim of the probe. Ablative temperatures were reached at the tip whereas the temperature of the metal connector near the rim of the sapphire crystal rose only 30 °C in blood when 15 W Nd-YAG was applied for 1 s. In contrast, the metal laser probe reached temperatures over 500 °C in an in vitro tissue/blood environment when 10 W was applied for 5 s. The metal probe ablated both in the forward and the radial direction. In a rabbit model there was a large variation in temperature of the metal in vivo (70 – 320 °C). The highest temperatures were associated with acute complications. However, in spite of transmural coagulation necrosis the artery wall remained functionally intact during a follow up period of up to 56 days.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276676
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  • 69
    Digitale Medien
    Digitale Medien
    Medical laser safety in the United Kingdom (1989)
    Springer
    Lasers in medical science 4 (1989), S. 177-179 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract Following a brief historical introduction the current status of Medical Laser Safety legislation and practise in the United Kingdom is outlined. Manufacturing and Administrative measures are specified both for public hospitals and private clinics
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276683
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  • 70
    Digitale Medien
    Digitale Medien
    Respiration triggered CO2 laser application in the Larynx — a a possibility to reduce the smoke inhalation of patients ? (1989)
    Springer
    Lasers in medical science 4 (1989), S. 139-141 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract The following is a report on a CO2 laser-respiration-triggering with its application in the larynx causing a reduction in the smoke load of the patient. From the result observed — an impro — ved suction capability and a reduced smoke-intensity in the ex —pired respiratory gas — it would appear that this method were suitable for practical application.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276678
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  • 71
    Digitale Medien
    Digitale Medien
    Medical laser in Greece (1989)
    Springer
    Lasers in medical science 4 (1989), S. 381-384 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract Although Laser technology has been around in Greece for quite some time, the medical and surgical application of Lasers has only recently started. However, the future seems to be promising due to the existence of advanced Laser Institutes, especially in Crete, the recent creation of the “Greek Medical Laser Society”, the increasing number of well trained physician, in the field of Laser and the expected close cooperation of all of the above.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276707
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  • 72
    Digitale Medien
    Digitale Medien
    Laser balloon angioplasty: An optical and thermal analysis (1989)
    Springer
    Lasers in medical science 4 (1989), S. 63-82 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract Our theoretical assessment of laser balloon angioplasty (LBA) begins with a solution of the popular P1 (diffusion) approximation to the radiative transport equation to map the optical field in an axisymmetric, finite annulus surrounding an infinitely long hollow cylindrical vessel. The inner surface is irradiated by diffuse light at 1.06 μm and delivered by a spiral segment of fiberoptic positioned centrally inside an inflated balloon. The present model considers only a single layer of optically homogenous arterial wall because the hollow is presumbly filled with a non-absorbing and non-scattering fluid. The cylindrical enclosure collects reflected light and redirects it back onto the inner surface. Our model accounts for this ‘integrating’ behavior, unique to enclosures. Absorption of the laser light then raises tissue temperature. The resultant transient and spatial temperature distribution is calculated with an implicit Finite Difference algorithm based on the heat conduction equation. Multiple concentric layers, each with different thermal properties from the other, are considered. However, changes in optical and thermal properties with temperature, and thermal phase transitions have been omitted in the present model. Finally, the Arrhenius rate process integral is applied for damage calculations. The temperature patterns of three delivery dose patterns — constant 22.5W (20s), ramp sequences of 40W(5s)-30W(5s)-10W(10s), and 35W(5s)-25W(5s)-15W(10s) — suggest that the second ramp dose may be most efficacious because it generates the longest temperature ‘plateau’ at the intimal-medial junction. Simulations of a hot metallic probe have a consistently higher surface damage than that obtained by LBA of equivalent energy output.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276670
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  • 73
    Digitale Medien
    Digitale Medien
    Application of 308 nm excimer laser radiation for ocular surgery — Safety considerations (1989)
    Springer
    Lasers in medical science 4 (1989), S. 129-138 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract Transmitting 308 nm excimer laser radiation via quartz fibers allows one to perform several surgical procedures inside the eye and on the cornea. A special application tip has been developed for each procedure. 308 nm radiation may damage the lens and the retina of the eye. UV absorbing drugs have been successfully used in in-vitro experiments to reduce the UV exposure of intraocular structures sensitive to 308 nm radiation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276677
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  • 74
    Digitale Medien
    Digitale Medien
    Beam delivery systems (1989)
    Springer
    Lasers in medical science 4 (1989), S. 155-158 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract Fibre optic systems, micromanipulator optics and articulated arms are described with particular emphasis on safety,limitations and areas of likely failure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276680
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  • 75
    Digitale Medien
    Digitale Medien
    Experience with laser safety in the USA-a review (1989)
    Springer
    Lasers in medical science 4 (1989), S. 165-175 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract Following several research programs in the 1960's aimed at studying the adverse biological effects of lasers and other optical radiation sources, laser occupational exposure limits were set and general safety standards were developed. Today, the experience from laser accidents and the development of new lasers and new applications have altered the format of the exposure limits and the safety procedures. It is critically important to distinguish between different biological injury mechanisms. The biological effects of ultraviolet radiation upon the skin and eye are additive over a period of at least one workday, and require different safety procedures. The scattered UV irradiance from excimer lasers may be quite hazardous, depending upon wavelength and action spectra. Since laser technology is young, the exposure of an individual in natural sunlight must be studied to evaluate the potential for chronic effects. The safety measures necessary in the use of lasers depend upon a hazard evaluation. The appropriate control measures and alternate means of enclosure, baffling, and operational control measures are presented. Present laser safety standards are explained briefly. Eye protective techniques and eyewear are considered for a variety of sources. The optical properties of enclosure materials are also discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276682
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  • 76
    Digitale Medien
    Digitale Medien
    Laser safety regulations and recommendations in Denmark (1989)
    Springer
    Lasers in medical science 4 (1989), S. 201-204 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract The Danish National Regulations are worked out by The Ministry of Labour. The regulations are not expressed in a clear form and guidelines for laser use in medical treatment rest more or less on the interpretation of legal and ethical regulations for medical personnel applicable in other areas. These regulations will be presented. Common Laser regulations for the EEC in cooperation with the ELA are suggested.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276686
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  • 77
    Digitale Medien
    Digitale Medien
    Laser Safety Standards and Safety Regulations for medical practise (1989)
    Springer
    Lasers in medical science 4 (1989), S. 229-234 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract A short survey on the development of the Laser Safety Regulations and Standards in the GDR is given. The last step is the adaptation of the IEC 325 document as the basis of national Laser Safety Standards. This basis is completed by guide-lines covering the general national requirement as well as special regulations for safe use of lasers in medical practise.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276690
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  • 78
    Digitale Medien
    Digitale Medien
    French standards on medical laser equipment (1989)
    Springer
    Lasers in medical science 4 (1989), S. 253-259 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract In France, the safety problems resulting from the therapeutic use of Laser are controled by two Standards NFC 74-311 and 312 These one are analysed. On the other hand an User's Guide which will be in the next edition as as appendice of the NFC 74-312 Standard is presently under consideration by the French committe. This one is analysed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276695
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  • 79
    Digitale Medien
    Digitale Medien
    New directions in Medical laser concept: role of laser-tissue interaction modelization and feedback control (1989)
    Springer
    Lasers in medical science 4 (1989), S. 317-327 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract Thermal lasers are used in many specialties. Clinical use of lasers is complicated by variations in tissue characteristics or hazards such as movement. Pionners in this field, relying on experimental work, have mastered the therapeutic use of lasers. Nevertheless, teaching such poorly defined technique has proved to be very difficult. To widespread the use of lasers, it is necessary to work in new directions. The goal is to give the practitioner a real medical tool, which should be cheap, easy and safe to use.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276698
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  • 80
    Digitale Medien
    Digitale Medien
    Endoscopic laser therapy (E.L.T.) at the National Cancer Institute, Milan: Current trends and new ideas (1989)
    Springer
    Lasers in medical science 4 (1989), S. 351-358 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract Presently, ELT is used 1) for the palliation of symptoms related to advanced cancer and 2) for the cure of benign tumors, vascular lesions, and early cancers in high surgical risk patients. The clinical use of new laser applications such as lithotripsy, hyperthermia, fluorescence, and tissue welding will parallel the development of new technologies in laser sources, optic fibers, and endoscopes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276701
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  • 81
    Digitale Medien
    Digitale Medien
    Laser training and accredentiation in Denmark (1989)
    Springer
    Lasers in medical science 4 (1989), S. 375-379 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276706
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  • 82
    Digitale Medien
    Digitale Medien
    Fields of training in the Laser Platform of Rueil-Malmaison (1989)
    Springer
    Lasers in medical science 4 (1989), S. 397-399 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract Our Laser Platform reaches more than 9 years of surgical experience, using the CO2 and the Nd:YAG lasers in a multidisciplinary way. By the end of September 1988, 2609 surgical laser procedures have been performed. Bronchoscopic and GI endoscopic laser procedures are not included in this data. Since 3 years, the laser sessions of the annual French Surgical Association Congress are under our responsability. This paper relates the previous laser workshops programs and details the forthcoming workshop on Lasers in Proctology.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276709
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  • 83
    Digitale Medien
    Digitale Medien
    In comparison: 1.064 μm-1.318 μm Nd-YAG continuous wave lasers. In vitro and in vivo experiments for endoscopic tumour therapy in the gastrointestinal tract (1989)
    Springer
    Lasers in medical science 4 (1989), S. 25-31 
    Details
    ISSN: 1435-604X
    Schlagwort(e): 1.318μm Nd-YAG laser ; Laser tissue effects ; New wavelength
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract In in vitro and animal experiments the tissue effects of the 1.318μm Nd-YAG laser were compared to those of the standard 1.064μm Nd-YAG laser in order to evaluate the advantages of the new wavelength with a ten times higher absorption in water for gastroenterological tumour treatment. Under irradiation parameters related to clinical endoscopic practice, the laser of the wavelength 1.318μm needs for both vaporization and coagulation significantly less energy than the 1.064μm laser. Since vaporization at 1.318μm is always accompanied by a higher coagulation effect compared to 1.064μm the risk of late necrosis and resulting perforation appears to be increased.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032506
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  • 84
    Digitale Medien
    Digitale Medien
    A mathematical model for interstitial laser treatment of tumours using four fibres (1989)
    Springer
    Lasers in medical science 4 (1989), S. 41-53 
    Details
    ISSN: 1435-604X
    Schlagwort(e): Mathematical model ; Laser surgery ; Optical fibres ; Tumours ; Thermal diffusion ; Multiple fibres
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract A mathematical model is employed to discuss the region treated by local hyperthermia, when the source of heat is a laser whose energy is directed into the treatment region through four optical fibres ending at the corners of a square. If treatment is over a period that is substantially longer than the time for the temperature distribution to reach equilibrium, a steady state model using four point sources can be employed to obtain a general idea of the temperatures reached and the region treated for different power levels and sizes of square. For shorter times, and for more accurate estimation of the regions treated, numerical calculation on a computer is essential. The details of the calculation depend on individual cases, but we demonstrate here that such computations are possible, and present a series of typical results. A comparison is made with the results of a series of experiments on canine liver, showing that it is possible to obtain good qualitative and numerical agreement.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032508
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  • 85
    Digitale Medien
    Digitale Medien
    A mathematical analysis of the results of experiments on rats' livers by local laser hyperthermia (1989)
    Springer
    Lasers in medical science 4 (1989), S. 55-64 
    Details
    ISSN: 1435-604X
    Schlagwort(e): Laser hyperthermia ; Mathematical model ; Tumours ; Optical coefficients ; Optical fibres ; Thermal diffusion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract A time dependent mathematical model of optical energy transfer and heat conduction in tissue with strong anisotropic scattering is used to analyse the results of experiments (1) in which the livers of rats were treated by local laser hyperthermia. Good qualitative agreement to the temperature distribution is possible, but satisfactory quantitative agreement is only possible if allowance is made for temperature dependence of the optical and thermal parameters. Analysis of the volume of tissue killed by the treatment shows a marked departure from the rule used in conventional hyperthermia to determine the region treated; the reason for this is not clear, but a number of possibilities are suggested.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02032509
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  • 86
    Digitale Medien
    Digitale Medien
    Editorial (1989)
    Springer
    Lasers in medical science 4 (1989), S. 1-2 
    Details
    ISSN: 1435-604X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276662
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  • 87
    Digitale Medien
    Digitale Medien
    Metamodel: A key to intelligent CAD systems (1989)
    Springer
    Research in engineering design 1 (1989), S. 19-34 
    Details
    ISSN: 1435-6066
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Technik allgemein
    Notizen: Abstract We introduce the metamodel as a new modeling framework for design objects based on General Design Theory, a mathematical model of design. Using General Design Theory, the metamodel concept can serve three functions: (1) as a central modeling mechanism to integrate models, (2) as a mechanism for modeling physical phenomena, and (3) as a tool for describing evolving design objects. Modeling with multiple points of view is realized by representing physical phenomena that occur in the deisng object and by constructing models with knowledge of physics and design from the metamodel. We illustrate the first and second functions of metamodels with an example based on naive physics, and we illustrate the third function of the metamodel through design experiments. Finally, we present two systems to illustrate how the metamodel mechanism can be implemented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01580000
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  • 88
    Digitale Medien
    Digitale Medien
    A framework for design problem-solving (1989)
    Springer
    Research in engineering design 1 (1989), S. 75-86 
    Details
    ISSN: 1435-6066
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Technik allgemein
    Notizen: Abstract We develop atask-structure for design problem-solving. The task-structure of a complex problemsolving activity such as design is a hierarchical organization of subtasks. For each task in the task-structure, we can then proceed to investigate whatmethods may be available, and what knowledge and inference requirements each of these methods have. Some of the methods may be domain-specific, some of them more generic in character, some may involve traditional computational techniques, and some others may involve searching in a problem space for solutions to the task. However, this systematic process of identifying tasks, methods, and subtasks will help us to see how design as a general problem is solved not by one method or technique but by an opportunistic exploitation of whatever methods are available (i.e., theknowledge required for using a method is available) to help accomplish a subtask. Thus, in principle, very different methods and knowledge can be brought into play in as flexible a way as applicable. For design problem-solving, we provide such an analysis for a family of design methods that we callpropose-verify-critique-modify methods. We end with remarks about how these methods can be flexibly integrated in a control structure that matches the subtasks with methods for which knowledge is available.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01580202
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  • 89
    Digitale Medien
    Digitale Medien
    Announcements (1989)
    Springer
    Research in engineering design 1 (1989), S. 145-146 
    Details
    ISSN: 1435-6066
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01580207
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  • 90
    Digitale Medien
    Digitale Medien
    Anticancer agent development: X-ray crystal structure and keto-enol tautomerism of dimethyl 1-hydroxy-6,7-methylenedioxy-4-(3′,4′,5′-trimethoxyphenyl-trans-3,4-dihydronaphthalene-2,3-dicarboxylate (1989)
    Springer
    Journal of chemical crystallography 19 (1989), S. 135-145 
    Details
    ISSN: 1572-8854
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract Structural and conformational information obtained from the crystal structure and solution1H nmr investigations of the title compound are compared. The 4-aryltetralone, C24H24O10, crystallizes as a chloroform solvate in the monoclinic space group, P21/n, witha=12.519(4),b=17.938(6),c=12.534(9)Å,β=111.90(5)°, and Dcalc=1.51 g cm−3 forZ=4. The data for this compound were collected at −150°C. Least-squares refinement of 2796 observed [F o≥5σ(F o)] reflections led to the final agreement index ofR=0.062. A threefold static disorder was observed for one of the carboxyl groups. The second carboxyl group participates in an intramolecular hydrogen bond and is thus ordered. The1H nmr spectrum revealed the title compound to exist as a keto-enol tautomeric mixture in solution. Vicinal hydrogen coupling constant analysis proved reliable in ascertaining B-ring stereochemistry of 2,3-disubstituted-4-aryltetralones.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01160850
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  • 91
    Digitale Medien
    Digitale Medien
    A far infrared investigation of anionic species present in solution during the crystallization of a polynuclear bromocuprate(I) cluster containing three-coordinated copper (I) (1989)
    Springer
    Journal of chemical crystallography 19 (1989), S. 147-157 
    Details
    ISSN: 1572-8854
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract Ethanolic solutions of tetrapropylammonium bromide and copper(I) bromide, from which bis(tetrapropylammonium) hexa-μ-bromo-tetrahedro-tetracuprate(I), [N(C3H7)4]2[Cu4Br6], a bromocuprate(I) cluster comprised of three-coordinated copper(I), crystallizes have been shown, by means of far i.r. spectroscopy, to contain the centrosymmetric, monomeric [CuBr2]− anion as the major, and probably the sole, bromocuprate(I) species,υ 3=323 cm−1. Crystalline [N(C3H7)4]2[Cu4Br6], [N(CH3)4]3[Cu2Br5] and [P(CH3)4]2[CuBr3], all of which contain anions in which copper(I) is three-coordinated, dissolve in nitro-methane to give solutions of the dibromocuprate(I) monomer. Variation of the coordination number of copper(I) in bromocuprates(I) crystallizing with symmetrically substituted quaternary ammonium and related unipositive cations is discussed in terms of dilution of the bromide ions by the cations, and a tentative mechanism for the formation of such compounds is proposed. Toward the end of the precipitation of [N(C3H7)4]2[Cu4Br6] from the ethanolic solution of tetrapropylammonium bromide and copper(I) bromide, a few crystals of a second bromocuprate(I) phase were obtained. This compound has been identified as tetrapropylammonium dibromocuprate(I), and its crystal structure determined from X-ray diffraction data. [N(C3H7)4][CuBr2] crystallizes in space groupP2/n, witha=13.010(15),b=7.577(5),c=8.858(4) Å,β=91.09(7)° andZ=2. The anion is a monomer in which Cu-Br is 2.194(3) Å and Br-Cu-Br 178.4(1)°, copper(I) being situated on a twofold axis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01160851
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  • 92
    Digitale Medien
    Digitale Medien
    Crystal and molecular structure of 17-β-methyl-α-isolupanineN-(16)-oxide perchlorate monohydrate (1989)
    Springer
    Journal of chemical crystallography 19 (1989), S. 193-201 
    Details
    ISSN: 1572-8854
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract [C16H27N2O2]+·ClO 4 − ·H2O,M r=396.87, orthorhombicP212121 a=13.708(4),b=16.930(7),c=8.311(3) Å,V=1928.3(13) Å3,Z=4,D x=1.367(2) g cm−3,λ(MoKα)=0.71068 Å,μ(MoKμ)=1.95 cm−1,F(000)=848,T=292 K,R=0.061 for 1324 unique reflections. RingsA,B,C,D have half-chair, chair, chair and chair conformations, respectively; the quinolizidone moietyA/E has a quasi-trans and the quinolizidine moietyC/D has a trans configuration. The cations are connected into chains along the crystallographic direction [001] by strong hydrogen bonds utilizing the water molecule: C(2)=O(5)⋯O(W)⋯O(6)-N(16) of 2.623(7) and 2.574(7) Å, respectively. The water molecule is also hydrogen-bonded to one oxygen atom of the perchlorate anion: O(W)⋯O(2) is 3.106(10) Å. A very short intramolecular distance between N(1) and O(6) of 2.696(7) Å, due to the quasitrans-trans configuration of theα-isolupanine skeleton, is observed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01160856
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  • 93
    Digitale Medien
    Digitale Medien
    Crystal and molecular structure of 4-aminoacetyl-N-p-nitrophenylsulfanilamide (1989)
    Springer
    Journal of chemical crystallography 19 (1989), S. 289-298 
    Details
    ISSN: 1572-8854
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The crystal and molecular structure of 4-aminoacetyl-N-p-nitrophenylsulfanilamide (C14H13N3O5S), a derivative of sulfonamide, has been determined from X-ray diffraction data using Cu-Kα radiation. The compound crystallised in the monoclinic space groupP21/c, witha=12.258(9),b=7.339(5),c=16.359(9) Å,β=98.84(4)°. The structure was solved by direct methods and refined by full-matrix least-squares to a finalR value of 0.047 with 2487 unique reflections. In packing, the molecules are found to be stabilised by N-H⋯ O hydrogen bonds.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01194124
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  • 94
    Digitale Medien
    Digitale Medien
    Crystal structure oftrans-[PtCl2(Me2PhP)(cis-2,5-dimethylpyrrolidine)] (1989)
    Springer
    Journal of chemical crystallography 19 (1989), S. 299-306 
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    ISSN: 1572-8854
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The complextrans-[PtCl2 (Me2PhP)(cis-2,4-dimethylpyrrolidine)] has been characterized by X-ray crystallography. It crystallizes in the monoclinic space group P 22/c witha=8.762(3),b=16.034(5),c=12.600(4)Å,β=93.43(3)° andZ=4. The structure was solved by heavy atom method and refined toR=0.052 for 3251 observed counter reflections. The coordination sphere of the Pt atom is square-planar with a geometry very similar to that of the studied complexes of the type trans-[PtCl2(R3P)L] whereL is either one of the possible isomers of theC,C′-dimethylpyrrolidine or the unsubstituted pyrrolidine. In the present complex the puckered five-membered ring of the dimethylpyrrolidine ligand assumes an envelope conformation with the maximum puckering at the N atom.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01194125
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  • 95
    Digitale Medien
    Digitale Medien
    Vibrational spectra and thermodynamic properties of 2,4,6-tribromobenzonitrile (1989)
    Springer
    Journal of chemical crystallography 19 (1989), S. 671-681 
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    ISSN: 1572-8854
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The infrared and Raman spectra of 2,4,6-tribromobenzonitrile have been recorded in the solid state and in solutions. Assignments of the fundamental vibrations based on Raman polarization data and comparison with the spectra of benzonitrile and its trichloro derivative are given and discussed. The thermodynamic functions have been evaluated for a rigid-rotor harmonic oscillator approximation at several temperatures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01179839
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  • 96
    Digitale Medien
    Digitale Medien
    Geometric alignment in the structure of 6,8-dichloro-2-trichloromethyl-4-dichloromethylene-1,3-benzdioxin consistent with incipientcis-elimination of HCl (1989)
    Springer
    Journal of chemical crystallography 19 (1989), S. 661-670 
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    ISSN: 1572-8854
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract Crystals of the title compound are monoclinic, P21/c, a=11.464(14),b=21.027(9),c=12.806(3) Å,β=108.00(6)°,V=2935.85 Å3,Z=8. The structure was solved by direct methods, from data collected at room temperature on an Enraf-Nonius CAD4 diffractometer, and refined by full matrix least squares to a finalR value of 0.089 using 3949 reflections. The two nonequivalent molecules are both disordered to the same extent, the ratio of the two models being 0.8∶0.2. In the minor model the substituent hydrogen atom at the 2-position is exactly eclipsed by a chlorine atom in the 2-CCl3 group whereas in the major model the normal staggered conformation is observed. C-Cl bond lengths and C-C-Cl angles in the major model are normal whereas those in the minor model are C-Cl(A) 1.51(3), C-Cl(B) 1.67(3), C-Cl(C) 1.95(3) Å, where Cl(C) is eclipsed, for one molecule and 1.85(3), 1.67(3), 1.94(2) Å for the other. Corresponding C-C-Cl bond angles (deg) are 115(1), 114(1), 80(1); and 120(1), 126(1), 90(1). A comparison is given with a structure which is not disordered but in which similar changes in the geometry of a∶CCl.CCl3 group are found.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01179838
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  • 97
    Digitale Medien
    Digitale Medien
    Crystal structure of racemic 5-(p-nitrobenzoylamino)-5-methyl-4-oxo-1,3-dioxane (1989)
    Springer
    Journal of chemical crystallography 19 (1989), S. 695-700 
    Details
    ISSN: 1572-8854
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract C12H12N2O6 crystallized from methanol in the monoclinic space group P21/c (Z=4) witha=13.333(4),b=10.154(3),c=9.597(2) Å andβ=102.37(2)°.M r=280.24,V=1269.1(6) Å3,D x=1.466 g cm−3,λ(Mo Kα)=0.71069 Å,μ=1.29 cm−1,T=295 K. The structure was solved by direct methods and refined by full-matrix least-squares to a finalR (R w)=0.049 (0.057) for 916 observed reflections. The molecules are linked by strong N-H⋯O(4) hydrogen bonds with N⋯O distance of 2.995(4) Å. The infinite racemic chains run in [001] direction.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01179841
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  • 98
    Digitale Medien
    Digitale Medien
    Crystal structure of the diacetate of (+)-epipinoresinol, C24H26O8 (1989)
    Springer
    Journal of chemical crystallography 19 (1989), S. 733-744 
    Details
    ISSN: 1572-8854
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The crystal structure of the diacetate of (+)-epipinoresinol, C24H26O8, has been determined by single-crystal diffraction methods. The compound crystallizes in the monoclinic space groupP21 witha=7.506(3),b=8.526(4),c=17.746(8) Å,β=97.12(4)° andZ=2. A total of 3504 reflexion intensities were recorded on a Syntex P21 diffractometer (MoKα radiation) at room temperature. The structure was solved by direct methods and electron density calculations. Full-matrix least-squares refinement gaveR=0.056 for 2297 observed [I〉3σ(I] reflexions. The individual central tetrahydrofuran rings have envelope conformations with coplanar carbon atoms and the oxygen atoms as flaps; the carbon atom planes form an angle of 119.9(3)°. Bond distances are C-C (aromatic) 1.386(12) Å, C(sp 3)-O 1.421(12) Å, C(sp 2)-O 1.372(20) Å, and C(sp 2)=O 1.186(9) Å. The influence of molecular structure on the positions of signals in the1H nmr spectrum of the diacetate of (+)-epipinoresinol is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01179846
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  • 99
    Digitale Medien
    Digitale Medien
    Crystal and molecular structure ofp-chlorothymols, I: 4-chloro-2-isopropyl-5-methylphenol (PCNT) (1989)
    Springer
    Journal of chemical crystallography 19 (1989), S. 765-773 
    Details
    ISSN: 1572-8854
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01179849
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  • 100
    Digitale Medien
    Digitale Medien
    Crystal structure of a decahydroquinoline thiocarbamate derivative (SR33434) with anticalcic properties (1989)
    Springer
    Journal of chemical crystallography 19 (1989), S. 775-785 
    Details
    ISSN: 1572-8854
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01179850
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