Problems encountered under the syntactic analysis of free text documents are discussed. As these problems are of general interest in nonautomatic or automatic syntactic indexing or search systems, these problems are presented in detail. The system called COPSY (context operator syntax), which uses natural language processing techniques during fully automatic syntactic analysis (indexing and search) of free text documents is described. Applications under real world conditions are mentioned as well as evaluation and technical aspects. Further developments in the field of thesaurus building and full-text analysis using the linguistic algorithms of the syntactic retrieval system are outlined. COPSY was developed as part of a text processing project at Siemens, called TINA (Text-/n halts-Analyse: text content analysis). Software from TINA is actually being tested by the U.S. Department of Commerce for patent search and indexing.Traditional Techniques "Precision-oriented devices involve using term phrases instead of single terms" (Salton, 1986) and their development is being pursued more and more intensely (Doszkocs, 1986). The crucial issues that term combination (i.e., syntactic indexing and search) deals with are fundamental problems in information retrieval. Therefore, we will begin by discussing some general problems that arise in this context, in particular postcoordination and precoordination. PostcoordinationTo simulate syntactic relations between search terms, commercial information retrieval systems use context operators in order to get better results with regard to precision. Apart from this technique there is the possibility of building more sophisticated inverted files that invert free text search terms in "narrower" units than documents or even paragraphs: the inversion is organized on the sentence level. In this case, the Boolean AND search looks for terms within sentence boundaries using the operator often called "WITH." This technique, too, can be regarded as a Received June 9, 1987; revised March 3, 1988; accepted July 11. 1988. C 1990 very crude means of doing a kind of pseudo-syntax by grouping terms close together.These well known techniques allow a post-coordinate search which combines search terms on-line. The advantage of searching in this manner is that the producers of information retrieval software do not really have to offer new systems. Instead they need only integrate more complex inverted files with more specific search sections (paragraphs, sentences) where search terms can be found using Boolean AND. Integrating word position numbers in context operator searches (often called "ADJACENT" or, more general, "NEAR") on the other hand does not imply a new concept in inverted file constructions.The disadvantages of the above mentioned search facilities are well known to searchers: complicated search logics have to be built up by the searcher and he or she is more or less forced to predict formulations his or her search question might have in the free text documents.If the searcher is lookin...

The DLR internal project "Next Generation Train" (NGT) deals with a high-speed train in a double-deck configuration. To realize the two continuous floors, a single wheel running gear configuration is selected. Equipped with independently rotating wheels instead of a usual wheel-set, a track guidance control becomes necessary. In terms of an advanced control and observer development the implementation of validated simulation models is absolutely essential. Therefore, the paper gives a short overview of the hardware of the scaled Experimental Running Gear on the DLR roller rig representing the NGT single wheel running gear. Using the DLR RailwayDynamics Library three different models of the running gear are implemented, which vary in complexity and can be used for different analysis methods. Finally, some significant simulation results of the particular simulation models are presented and discussed.

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State observer design turned out to be crucial in several recent railway vehicles projects on active control and condition monitoring at DLR, but may also be useful for emerging technologies like the cyber physical system and the digital twin approach or the realization of predictive maintenance concepts. With this background and motivation the paper presents a process in three steps: (i) an initial analysis results in a physical model, (ii) the subsequent transfer to state space representation facilitates the prove of observability and (iii) the observer synthesis supports the design of the observer feedback law. Results from two projects, one related to longitudinal or traction dynamics, the other associated to the guidance task of independently rotating wheels, demonstrate the application of the observer design process and offers a comparison of observer estimates with measurements.