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Hybrid systems are the result of merging the two most commonly used models for dynamical systems, namely continuous dynamical systems defined by differential equations and discrete-event systems defined by automata. One can view hybrid systems as constrained systems, where the constraints describe the possible process flows, invariants within states, and transitions on the one hand, and to characterize certain parts of the state space (e.g. the set of initial states, or the set of unsafe states) on the other hand. Therefore, it is advantageous to use constraint logic programming (CLP) as an approach to model hybrid systems. In this paper, we provide CLP implementations, that model hybrid systems comprising several concurrent hybrid automata, whose size is only straight proportional to the size of the given system description. Furthermore, we allow different levels of abstraction by making use of hierarchies as in UML statecharts. In consequence, the CLP model can be used for analyzing and testing the absence or existence of (un)wanted behaviors in hybrid systems. Thus in summary, we get a procedure for the formal verification of hybrid systems by model checking, employing logic programming with constraints.
The STOR project aims at the development of a scientific component system employing models and knowledge for object recognition in images. This interim report elaborates on the requirements for such a component system, structures the application area by identifying a large set of basic operations, and shows how a set of appropriate data structures and components can be derived. A small case studies exemplifies the approach.
Abstract The present work investigates the wetting characteristics of soils with regard to their dependence on environmental parameters such as water content (WC), pH, drying temperature and wetting temperature of wettable and repellent soils from two contrasting anthropogenic sites, the former sewage disposal field Berlin-Buch and the inner-city park Berlin-Tiergarten. The aim of this thesis is to deepen the understanding of processes and mechanisms leading to changes in soil water repellency. This helps to gain further insight into the behaviour of soil organic matter (SOM) and identifying ways to prevent or reduce the negative effects of soil water repellency (SWR). The first focus of this work is to determine whether chemical reactions are required for wetting repellent samples. This hypothesis was tested by time and temperature dependence of sessile drop spreading on wettable and repellent samples. Additionally, diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy was used to determine whether various drying regimes cause changes in the relative abundance of hydrophobic and hydrophilic functional groups in the outer layer of soil particles and whether these changes can be correlated with water content and the degree of SWR. Finally, by artificially altering the pH in dried samples applying acidic and alkaline reagents in a gaseous state, the influence of only pH on the degree of SWR was investigated separately from the influence of changes in moisture status. The investigation of the two locations Buch and Tiergarten, each exceptionally different in the nature of their respective wetting properties, leads to new insights in the variety of appearance of SWR. The results of temperature, water content and pH dependency of SWR on the two contrasting sites resulted in one respective hypothetical model of nature of repellency for each site which provides an explanation for most of the observations made in this and earlier studies: At the Tiergarten site, wetting characteristics are most likely determined by micelle-like arrangement of amphiphiles which depends on the concentration of water soluble amphiphilic substances, pH and ionic strength in soil solution. At low pH and at high ionic strength, repulsion forces between hydrophilic charged groups are minimized allowing their aggregation with outward orientated hydrophobic molecule moieties. At high pH and low ionic strength, higher repulsion forces between hydrophilic functional groups lead to an aggregation of hydrophobic groups during drying, which results in a layer with outward oriented hydrophilic moieties on soil organic matter surface leading to enhanced wettability. For samples from the Buch site, chemical reactions are necessary for the wetting process. The strong dependence of SWR on water content indicates that hydrolysis-condensation reactions are the controlling mechanisms. Since acid catalyzed hydrolysis is an equilibrium reaction dependent on water content, an excess of water favours hydrolysis leading to an increasing number of hydrophilic functional groups. In contrast, water deficiency favours condensation reactions leading to a reduction of hydrophilic functional groups and thus a reduction of wettability. The results of the present investigation and its comparison with earlier investigations clearly show that SWR is subject to numerous antagonistically and synergistically interacting environmental factors. The degree of influence, which a single factor exerts on SWR, is site-specific, e.g., it is dependent on special characteristics of mineral constituents and SOM which underlies the influence of climate, soil texture, topography, vegetation and the former and current use of the respective site.
This thesis deals with the verbal categories tense and aspect in the context of analysing the English perfect. The underlying notion of time is examined from the viewpoint of etymology and from the viewpoint of fields of knowledge that lie outside the immediate scope of temporal semantics, e.g. mathematics. The category tense is scrutinised by discussing the concept of Reichenbach tense and the concept of correlation (Giering). The starting point of the discussion of the category verbal aspect is the dichotomy perfective vs. imperfective in the Slavic languages. The main part about the perfect is concerned with the possessive perfect as a cross-linguistic phenomenon (including a comparison of the English and the Slavic perfect) and focuses on the usage and the meaning of the English present perfect. There are three appendices which are an integral part of this dissertation. Appendix A deals with the systematization of English verb forms and their graphical representation. Three different visualizations are presented, two of which are genuine to this paper. Appendix B reproduces the target setting according to which an animated visualization of English infinitives was programmed. Appendix C represents a synopsis of approaches to the English perfect in grammars and textbooks.
The genus Cheilolejeunea (Spruce) Schiffn. (Lejeuneaceae, Jungermanniopsida) is represented by 23 species in continental tropical Africa. The morphological characters such as features of the stem, leaf, lobule and perianth traditionally used to separate the taxa at both species and generic level have been found to be unstable. The species are variably ranked in several subgenera including Cheilolejeunea (Spruce) Schiffn., Euosmolejeunea Schiffn., Strepsilejeunea (Spruce) Schiffn. and Xenolejeunea Kachroo & Schust. Although the genus has never been monographed, there are a few regional taxonomic accounts for America, Australia and China. A comprehensive revision of Cheilolejeunea species is lacking in Africa where the existing studies are based on single subgenus and sub-regional flora or checklist compilations, which are sometimes without identification keys. This study revises the taxonomy of Cheilolejeunea and the closely allied genus Leucolejeunea A. Evans, in continental Africa based on morphological data analysed using phenetic and phylogenetic methods.
The research described in this thesis was designed to yield information on the impact of particle-bound pesticides on organisms living in the interface between sediment and water column in a temporarily open estuary (TOCEs). It was hypothesized that natural variables such as salinity and temperature and anthropogenic stressors such as particle-bound pesticides contribute to the variability of the system. A multiple line of evidence approach is necessary due to the variability in sediment type, contaminant distribution and spatial and temporal variability within the ecosystem in particular within TOCEs. The first aim of this thesis was to identify which particle-bound pesticides are important to the contamination of the Lourens River estuary (Western Cape, South Africa), taking into account their environmental concentrations, physico-chemical and toxicological properties (Exposure assessment). The second aim was to identify spatial and temporal variations in particle bound pesticide contamination, natural environmental variables and benthic community structure (effect assessment). The third aim was to test the hypothesis: "does adaptation to fluctuating salinities lead to enhanced survival of the harpacticoid copepod Mesochra parva when exposed to a combination of particle associated chlorpyrifos exposure and hypo-osmotic stress during a 96 h sediment toxicity test?" The last aim was to identify the driving environmental variables (including natural and anthropogenic stressors) in a "natural" (Rooiels River) compared to a "disturbed" (Lourens River) estuary and to identify if and how these variables change the benthic community structure in both estuaries. Data produced in this research thus provide important information to understand the impact of pesticides and its interaction with natural variables in a temporarily open estuary. To summarise, this study indicated, by the use of the multi-evidence approach, that the pesticides endosulfan and chlorpyrifos posed a risk towards benthic organisms in a temporarily open estuary in particular during spring season. Furthermore an important link between pesticide exposure/ toxicity and salinity was identified, which has important implications for the management of temporarily open estuaries.
Many pharmaceuticals (e.g. antibiotics, contrast media, beta blockers) are excreted unmetabolized and enter wastewater treatment plants (WWTPs) through the domestic sewage system. Research has shown that many of them are not effectively removed by conventional wastewater treatment and therefore are detected in surface waters. Reverse osmosis (RO) is one of the most effective means for removing a wide range of micropollutants in water recycling. However, one significant disadvantage is the need to dispose the resultant RO concentrate. Due to the fact that there are elevated concentrations of micropollutants in the concentrate, a direct disposal to surface water could be hazardous to aquatic organisms. As a consequence, further treatment of the concentrate is necessary. In this study, ozonation was investigated as a possible treatment option for RO concentrates. Concentrate samples were obtained from a RO-membrane system which uses municipal WWTP effluents as feeding water to produce infiltration water for artificial groundwater recharge. In this study it could be shown that ozonation is efficient in the attenuation of selected pharmaceuticals, even in samples with high TOC levels (46 mg C/L). Tests with chlorinated and non-chlorinated WWTP effluent showed an increase of ozone stability, but a decrease of hydroxyl radical exposure in the samples after chlorination. This may shift the oxidation processes towards direct ozone reactions and favors the degradation of compounds with high apparent second order rate constants. Additionally it might inhibit an oxidation of compound predominantly reacting with OH radicals. Ozone reaction kinetics were investigated for beta blockers (acebutolol, atenolol, metoprolol and propranolol) which are permanently present in WWTP effluents. For beta blockers two moieties are common which are reactive towards ozone, a secondary amine group and an activated aromatic ring. The secondary amine is responsible for a pH dependence of the direct ozone reaction rate, since only the deprotonated amine reacts very quickly. At pH 7 acebutolol, atenolol and metoprolol reacted with ozone with an apparent second order rate constant of about 2000 M-1 s-1, whereas propranolol reacted at ~1.0 105 M-1 s-1. The rate constants for the reaction of the selected compounds with OH radicals were determined to be 0.5-1.0 x 1010 M-1 s-1. Oxidation products (OPs) formed during ozonation of metoprolol and propranolol were identified via liquid chromatography (LC) tandem mass spectrometry. Ozonation led to a high number of OPs being formed. Experiments were carried out in MilliQ-water at pH 3 and pH 8 as well as with and without the radical scavenger tertiary butanol (t-BuOH). This revealed the influence of pH and the OH radical exposure on OP formation. The OH radical exposure was determined by adding the probe compound para-chlorobenzoic acid (pCBA). Metoprolol: To define the impacts of the protonated and non protonated metoprolol species on OH radical formation, the measured pCBA attenuation was compared to modeled values obtained by a simplified kinetic model (Acuchem). A better agreement with the measured results was obtained, when the model was based on a stoichiometric formation of OH radical precursors (O2-) during the primary ozone reaction of metoprolol. However, for reaction of a deprotonated molecule (attack of the aromatic ring) a formation of O2- could be confirmed, but an assumed stoichiometric O2- formation over-estimated the formation of OH radicals in the system. Analysis of ozonated raw wastewater and municipal WWTP effluent spiked with 10 μM metoprolol exhibited a similar OP formation pattern as detected in the reaction system at pH 8 without adding radical scavenger. This indicated a significant impact of OH radical exposure on the formation of OPs in real wastewater matrices. Propranolol: The primary ozonation product of propranolol (OP-291) was formed by an ozone attack of the naphthalene ring, which resulted in a ring opening and two aldehyde moieties being formed. OP-291 was further oxidized to OP-307, presumably by an OH radical attack, which was then further oxidized to OP-281. Reaction pathways via ozone as well as OH radicals were proposed and confirmed by the chemical structures identified with MS2 and MS3 data. It can be concluded that ozonation of WWTP effluent results in the formation of a high number of OPs with an elevated toxic potential (i.e. formation of aldehydes).
This thesis evaluates automated techniques to remove objects from an image and proposed several modifications for the specific application of removing a colour checker from structure dominated images. The selection of approaches covers the main research field of image inpainting as well as an approach used in medical image processing. Their results are investigated to disclose their applicability to removing objects from structure-intense images. The advantages and disadvantages discovered in the process are then used to propose several modifications for an adapted inpainting approach suitable for removing the colour checker.
Colonoscopy is the gold standard for the detection of colorectal polyps that can progress into cancer. In such an examination, physicians search for polyps in endoscopic images. Thereby polyps can be removed. To support experts with a computer-aided diagnosis system, the University of Koblenz-Landau currently makes some efforts in research different methods for automatic detection. Comparable to traditional pattern recognition systems, features are initially extracted and a classifier is trained on such data. Afterwards, unknown endoscopic images can be classified with the previously trained classifier. This thesis concentrates on the extension of the feature extraction module in the existing system. New detection methods are compared to existing techniques. Several features are implemented, incorporating Graylevel Co-occurrence Matrices, Local Binary Patterns and Discrte Wavelet Transform. Different modifications on those features are applied and evaaluated.
In recent years, traceability has been more and more universally accepted as being a key factor for the success of software development projects. However, the multitude of different, not well-integrated taxonomies, approaches and technologies impedes the application of traceability techniques in practice. This paper presents a comprehensive view on traceability, pertaining to the whole software development process. Based on graph technology, it derives a seamless approach which combines all activities related to traceability information, namely definition, recording, identification, maintenance, retrieval, and utilization in one single conceptual framework. The presented approach is validated in the context of the ReDSeeDS-project aiming at requirements-based software reuse.