A Conceptual and Formal Framework for the Integration of Data Type and Process Modeling Techniques

A conceptual framework for the integration of data type and process modeling techniques, called integration paradigm, has been presented by the authors in previous papers already. The aim of this paper is to give a short review of this conceptual framework and to present a formal model for the integration paradigm. The formal model for the four layers, called data type, data states and transformations, processes and system architecture layers respectively, is based on an integration of abstract data types and structured transition systems. This formal model can be instantiated by all kinds of basic and integrated modeling techniques. Algebraic high-level nets, attributed graph transformation, an integration of Z with statecharts, and some diagram techniques of UML are discussed on the conceptual level. As instantiation of the formal model, a well-known CCS sender specification, place/transition nets, algebraic high-level nets and attributed graph transformation are presented in this paper, while instantiations of other modeling techniques will be discussed elsewhere.     

Liquid-crystalline polyesters with y-shaped mesogens: Phase structure pecularities

Summary Liquid crystalline (LC) main-chain polyesters with y-shaped mesogenic elements have been investigated by X-ray diffraction. The X-ray pattern of the glassy nematic polyester with the largest branching shows besides the reflections in the wide angle range corresponding to the average distance between the molecules also equatorial reflections in the small angle range. This is suggesting a spontaneous formation of microfibrils. X-ray pattern of the polymer above 150 °C points to the existence of a normal nematic phase. The proposed order-disorder model is supported by results of calorimetric measurements and mixing experiments with a low-molecularweight LC-compound.     

Reformulations of the shortest route model for dynamic multi-item multi-level capacitated lotsizing

The shortest route representation of the dynamic multi-item multi-level capacitated lotsizing problem is appealing due to the tight bound provided by its Linear Programming (LP) relaxation. However, it suffers from two main drawbacks: Firstly, even solving the LP relaxation of problem instances with up to 16 time periods and 40 items with standard mathematical programming software might require a prohibitive amount of computer time. Secondly, the quadratic growth of the number of variables with the number of periods restricts the solution of problem instances with many periods. Both drawbacks will be addressed in this paper by proposing reformulations of the original shortest route model. Especially we will introduce a model formulation which allows theuser to find a tradeoff between model size and tightness of the lower bound obtained by the LP relaxation by specifying the number oflook ahead periods . Furthermore, we will provide an iterative procedure for determining those look ahead periods which result in the tightest LP relaxation. Theoretical insights as well as computational results are provided, too.     

Analyse der potentiellen Explosionswirkung von kurzzeitig in die Atmosphäre freigesetzten Brenngasmengen. Teil I: Gesetze der Wolkenausbreitung und -deflagration aus Berstversuchen an Modellbehältern

Explosion hazard analysis of inflammable gas released spontaneously into the atmosphere . The processes of flash evaporation, atmospheric vapour cloud formation ignition and explosion after the bursting of vessels containing liquefied gas have been studied by model experiments with propylene heated up to 70°C and pressurized to 60 bar. The experiments have shown that a blast wave with considerable peak pressure in the vicinity of the vessel is produced already by flash expansion of the propylene. The experimentally determined decrease of peak pressure with growing distance could be scaled up to vessels of arbitrary size and different propylene temperatures. Scaling laws could be established as well for the calculation of peak pressure and positive pressure duration of the deflagration wave as functions of released mass and distance. The experiments have not revealed any evidence of a detonation process even when the cloud was ignited by an explosive charge.     

Mullite with Lattice Constants a > b

The mullite phase was synthesized in a sol–gel process using aluminum sec -butylate and silicon chloride in proportions corresponding to an Al/Si ratio of 4:1. Heat treatment at 1000°C yielded a mullite-type phase, γ-alumina, and amorphous fractions. Conventional indexing based on the orthorhombic ( Pbam ) mullite unit cell with b > a showed that X-ray diffraction peaks with high k and l but low h indices are strongly shifted toward higher d -spacings as compared with a "normal" mullite. Furthermore, the relative positions of reflection pairs hkl and khl are interchanged. The Rietveld analysis yielded the following constants: a = 7.760(2) Å, b = 7.595(2) Å, c = 2.9192(4) Å confirming a > b .     

Phase Composition, Oxygen Content, and Thermal Conductivity of AIN(Y2O3) Ceramics

An indirect method to determine the oxygen dissolved in AIN is devised for AIN(Y₂O₃) ceramics and then related to thermal conductivity. Dissolved oxygen is determined by first constructing the AIN-rich corner of the AIN—Y₂O₃—Al₂O₃ phase diagram (isothermal section). This is achieved by (1) measuring the total oxygen content and subtracting from it the oxygen in the Y₂O₃, resulting in a virtual alumina content; (2) placing the sample composition on the diagram; (3) determining the phases present by XRD for each sample; and (4) drawing phase boundaries which best agree with the phases present. The intersection of these tie lines through the sample location with the AIN—Al₂O₃ axis then gives the particular Al₂O₃ oxygen content dissolved in the AIN lattice. For the system AIN—Y₂O₃—Al₂O₃, it is shown that it is indeed this fraction of the total oxygen content that has a decisive limiting influence on thermal conductivity of dense, polyphase AIN ceramics.     

Current Density Reconstructions for Lorentz Force Evaluation

The detection and reconstruction of fatigue fractures is of great interest in quality assurance. In the framework of nondestructive testing, Lorentz force evaluation (LFE) is an evaluation technique to estimate flaws in electrically conductive materials based on measured Lorentz forces. In the forward solution for LFE, a defect can be interpreted as a distributed current source. This has motivated the authors to propose current density reconstructions (CDRs) calculated with minimum norm estimates to estimate defect geometries. The L₁ and L₂ norms tend to produce a solution which is either very focused or very smeared. To balance these constraints, the general L_p norm with 1 ≤ p ≤ 2 was used and the inverse solutions compared. This approach was applied to measured data obtained from a laminated composite and simulated data from a monolithic material. The results show that the L_1.5 norm provides the most accurate inverse solutions. The location and extent of the defect are determined with an error of 15 % relative to the size of the defect. The depth estimation has a deviation of 50 %. It can be concluded that CDRs are a powerful method to reconstruct and characterize defects in LFE.     

Mediana

This paper presents Mediana, a computer-based, integrated workbench for the management and analysis of media data supporting media researchers. Its main components are the recording and management of multimedia data (i.e. image, video and text data) in a database system, semi-automatical analysis tools for images and videos, and a graphical user interface (GUI) integrating all tools and components applied in media research.