Showing papers by "Karlsruhe Institute of Technology published in 1990"
TL;DR: In this paper, a convective modeling procedure is presented which avoids the stability problems of central differencing while remaining free of the inaccuracies of numerical diffusion associated with upstream differencings.
4,190 citations
TL;DR: Coprecipitation experiments suggest direct AP-1-hormone receptor interaction, which also possibly explains the reverse experiment: overexpression of Fos or Jun inhibits the expression of hormone-dependent genes.
1,576 citations
TL;DR: In this article, the influence of surface inhomogeneities on corrosion processes is demonstrated by electrochemical impedance spectroscopy (EIS), and experimental impedance data obtained in different systems are discussed on the basis of transfer function analysis.
648 citations
TL;DR: In this article, the rate of the resistance degradation of doped SrTiO3 ceramics is investigated as a function of various external and material parameters, including voltage, electric field, and thickness of the dielectric.
Abstract: The rate of the resistance degradation of doped SrTiO3 ceramics is investigated as a function of various external and material parameters. The effects of the mutually interrelated parameters dc voltage, dc electric field, and thickness of the dielectric are described by power laws. Electron microscopic potential contrast studies show a Maxwell-Wagner polarization leading to a concentration of the electric field at the grain boundaries during the degradation. Based on this finding, the voltage step per grain boundary, ΔΘgb, is introduced as a rate-determining parameter which allows an explanation of the influence of the grain size on the degradation rate as well as the difference in the power laws for ceramic and single-crystal samples.
602 citations
TL;DR: In this article, a quantitative model for dc voltage-induced resistance degradation is based on the defect structural material constants and a numerical solution of the general transport problem for the mixed-conducting perovskite-type titanates.
Abstract: A quantitative model for the dc voltage-induced resistance degradation is based on the defect structural material constants and a numerical solution of the general transport problem for the mixed-conducting perovskite-type titanates. During degradation, a demixing of the initially homogeneous oxygen vacancy concentration in nominally undoped and acceptor-doped systems occurs since the ionic transfer is (at least partially) blocked at the electrodes. Because of the specific defect structure, the concentration polarization of the oxygen vacancies leads to a pronounced increase of the p-conductivity in the anodic region and formation of an n-conducting cathodic region. The results of our phenomenological degradation studies concerning the influence of external parameters and material parameters as well as the time evolution of the field distribution and the electro-coloration are described by our simulation model with reasonable precision. The thermodynamic and kinetic aspects of the demixing process are discussed and compared to related phenomena.
396 citations
TL;DR: In this paper, a systematic analysis of B meson decays into pions has been performed for decay modes with 2−7 pions in the final state, and the upper limits obtained on various branching ratios are consistent with the current model predictions.
386 citations
TL;DR: In this article, numerical calculations of laminar vortex shedding flows past circular and square cylinders for Re less than or equal to 5000 in the former case and Re less or equal or equal 300 in the latter case were presented.
309 citations
TL;DR: In this paper, the resistance degradation of titanates is studied as a function of the temperature and the applied dc voltage, and the individual influence of the acceptor dopants is discussed.
Abstract: The resistance degradation of Al-doped, Ni-doped, and Fedoped SrTiO3 single crystals is studied as a function of the temperature and the applied dc voltage. The individual influence of the acceptor dopants is discussed. Data of the mobility of oxygen vacancies are obtained from the determination of the time evolution of the electric field distribution between the electrodes, from electrocoloration studies, and from an examination of the thermal annealing after degradation. In a numerical calculation based on the defect chemistry and transport properties of titanates, the electrocoloration process is simulated and a qualitative explanation of the degradation process is presented.
305 citations
TL;DR: The time series of classified European atmospheric circulation patterns for the time period of 1881-1989 are analyzed in this paper, where changes can be observed both in the annual frequencies and in the seasonal ones for many circulation types.
Abstract: The time series of classified European atmospheric circulation patterns for the time period of 1881–1989 are analyzed. Frequencies of several circulation types changed considerably during the last years, showing extremes never reached before. Changes can be observed both in the annual frequencies and in the seasonal ones for many circulation types. The time series were analyzed for homogeneity using non-parametric statistical methods. The annual cycle shows an increase of the frequency of zonal circulations in winter (December and January) and a corresponding decrease of cold meridional circulations. The climatological consequences of this are more frequent mild and humid winters in Central Europe, with precipitation mostly falling as rain. Change points in the series occurred with high probability during the seventies. Examples demonstrate the coupling of circulation patterns to temperature and precipitation.
266 citations
TL;DR: In this article, the structure of the tensor product representation of the quantum groupSLq(2,C) was investigated by using the 2-dimensional quantum plane as a building block.
Abstract: We investigate the structure of the tensor product representation of the quantum groupSLq(2,C) by using the 2-dimensional quantum plane as a building block. Two types of 4-dimensional spaces are constructed applying the methods used in twistor theory. We show that the 4-dimensional real representation ofSLq(2,C) generates a consistent non-commutative algebra, and thus it provides a quantum deformation of Minkowski space. The transformation of this 4-dimensional space gives the quantum Lorentz groupSOq(3, 1).
181 citations
TL;DR: In this article, the authors proposed two models that can explain the exposure on the ocean floor of the deep foundation of the oceanic crust. But both models require a larger amount of extension and emphasize asymmetry with denudation of the upper crust through low-angle detachment faulting.
TL;DR: In this paper, a new concept of inequality-equivalence, called intermediate, is presented, which allows one to vary the value judgement on inequality between the well-known relative and absolute views.
01 Oct 1990
TL;DR: A genetic algorithm for solving the traveling salesman problem by genetic algorithms to optimality for traveling salesman problems with up to 442 cities is presented.
Abstract: We present a genetic algorithm for solving the traveling salesman problem by genetic algorithms to optimality for traveling salesman problems with up to 442 cities. Muhlenbein et al. [MGK 88], [MK 89] have proposed a genetic algorithm for the traveling salesman problem, which generates very good but not optimal solutions for traveling salesman problems with 442 and 531 cities. We have improved this approach by improving all basic components of that genetic algorithm. For our experimental investigations we used the traveling salesman problems TSP (i) with i cities for i=137, 202, 229, 318, 431, 442, 666 which were solved to optimality in [CP 80], [GH 89].
01 May 1990
TL;DR: An analytical cost model for access support relations and their application is developed and is used to determine the best access support relation extension and decomposition with respect to the specific database configuration and application profile.
Abstract: In this work access support relations are introduced as a means for optimizing query processing in object-oriented database systems. The general idea is to maintain redundant separate structures (disassociated from the object representation) to store object references that are frequently traversed in database queries. The proposed access support relation technique is no longer restricted to relate an object (tuple) to an atomic value (attribute value) as in conventional indexing. Rather, access support relations relate objects with each other and can span over reference chains which may contain collection-valued components in order to support queries involving path expressions. We present several alternative extensions of access support relations for a given path expression, the best of which has to be determined according to the application-specific database usage profile. An analytical cost model for access support relations and their application is developed. This analytical cost model is, in particular, used to determine the best access support relation extension and decomposition with respect to the specific database configuration and application profile.
TL;DR: In this article, the authors show that in the central Kenya Rift the direction of extension rotated from east-west to northwest-southeast during the Pleistocene, and that dextral oblique reactivations along older normal faults and created new normal faults with dextrally oblique components.
Abstract: Displacement of stratigraphic units along major normal faults and the kinematics of minor faults show that in the central Kenya Rift the direction of extension rotated from east-west to northwest-southeast during the Pleistocene. Possibly controlled by lithospheric weaknesses in the Proterozoic basement, an early half graben bounded by east-northeast-dipping, northwest-and north-northwest-striking oblique normal faults developed between about 12 and 7 Ma. Between 5.5(?) and 4 Ma, west-southwest-dipping antithetic normal faults established a full graben, and after 3.3 Ma west-southwest-dipping and north-northwest-striking oblique normal faults separated a tectonically active inner rift from the intrarift Kinangop Plateau to the east. Analysis of minor fault data indicates a general north-south orientation for σ 2 until about 0.4 Ma; since then, a clockwise rotation of σ 2 into the north-northeast to northeast orientation appears to have taken place. This rotation caused dextral oblique reactivations along older normal faults and created new normal faults with dextrally oblique components. The new kinematic regime is compatible with regional seismicity, and possibly developed as a response to far-field tectonic stresses generated by spreading in the Gulf of Aden and the Red Sea.
TL;DR: In this article, the authors show that basalts from the axial trough of the Red Sea and from volcanic fields of the Arabian Peninsula ranging in composition from N-type MORB to basanite and in age from Early Miocene to Recent show a limited variation in their isotopic compositions.
01 Nov 1990
TL;DR: In Journal of Cryptology 1/1 (1988) 65–75, CHAUM describes a beautiful technique, the DC-net, which should allow participants to send and receive messages anonymously in an arbitrary network but that of the recipients implicitly assumes a reliable broadcast network.
Abstract: In Journal of Cryptology 1/1 (1988) 65–75, CHAUM describes a beautiful technique, the DC-net, which should allow participants to send and receive messages anonymously in an arbitrary network. The untraceability of the senders is proved to be unconditional, but that of the recipients implicitly assumes a reliable broadcast network. This assumption is unrealistic in some networks, but it can be removed completely by using the fail-stop key generation schemes by WAIDNER (these proceedings). In both cases, however, each participant can untraceably and permanently disrupt the entire DC-net.
01 Nov 1990
TL;DR: MIXes are a means of untraceable communication based on a public key cryptosystem, as published by David Chaum in 1981 (CACM 24/2, 84–88)
Abstract: MIXes are a means of untraceable communication based on a public key cryptosystem, as published by David Chaum in 1981 (CACM 24/2, 84–88) (=[6]).
TL;DR: This repression depends on conserved region 1, one of the transforming domains of E1a, indicating that it is an integral feature of adenovirus transformation, and is a unique property among dominant oncogenes.
TL;DR: This work compares two rather different approaches using third parties to provide security by third parties identifying perpetrators in cases of detected fraud, whereas the second uses a third party as trustee who takes an active part in the value exchange and can be completely controlled by each absolutely anonymous party.
TL;DR: It is shown that the problem can be solved using several distributions instead of a single one, and an efficient procedure for computing the optimized input probabilities is presented.
Abstract: The test of integrated circuits by random patterns is very attractive, since no expensive test pattern generation is necessary and tests can be applied with a self-test technique or externally using linear feedback shift registers. Unfortunately, not all circuits are random-testable, because either the fault coverage is too low or the required test length too large. In many cases the random test lengths can be reduced by orders of magnitude using weighted random patterns. However, there are also some circuits for which no single optimal set of weights exists. A set of weights defines a distribution of the random patterns. It is shown that the problem can be solved using several distributions instead of a single one, and an efficient procedure for computing the optimized input probabilities is presented. If a sufficient number of distributions is applied, then all combinational circuits can be tested randomly with moderate test lengths. The patterns can be produced by an external chip, and an optimized test schedule for circuits with a scan path can be obtained. Formulas are derived to determine strong bounds on the probability of detecting all faults. >
TL;DR: In this paper, it was shown that for small values of the molecular Peclet number no resistance at the rigid wall exists, and that the effect of lateral maldistribution of fluid velocity and/or thermal conductivity, of axial dispersion of heat, and of small, systematic errors in measurement is investigated.
TL;DR: Multifrequency electron paramagnetic resonance (EPR) spectra of the Cu(II) site in bovine heart cytochrome c oxidase (COX) and nitrous oxide reductase (N2OR) and Pseudomonas stutzeri confirm the existence of Cu‐Cu interaction in both enzymes.
TL;DR: It is showed that the problem of fuzzy regression can be formulated as a mathematical programming problem and the special case of linear regression yields a linear programming problem.
TL;DR: It is shown that testability is still guaranteed, even if only a small part of the flipflops is integrated into a scan path, and the overall test application time decreases in comparison with a complete scan path.
Abstract: The scan design is the most widely used technique used to ensure the testability of sequential circuits. In this article it is shown that testability is still guaranteed, even if only a small part of the flipflops is integrated into a scan path. An algorithm is presented for selecting a minimal number of flipflops, which must be directly accessible. The direct accessibility ensures that, for each fault, the necessary test sequence is bounded linearly in the circuit size. Since the underlying problem is NP-complete, efficient heuristics are implemented to compute suboptimal solutions. Moreover, a new algorithm is presented to map a sequential circuit into a minimal combinational one, such that test pattern generation for both circuit representations is equivalent and the fast combinational ATPG methods can be applied. For all benchmark circuits investigated, this approach results in a significant reduction of the hardware overhead, and additionally a complete fault coverage is still obtained. Amazingly the overall test application time decreases in comparison with a complete scan path, since the width of the shifted patterns is shorter, and the number of patterns increase only to a small extent.
TL;DR: Thechlorophyll-fluorescence ratio F690/F730 is a good indicator of the chlorophyll content and can be used as a non-destructive measure of the chlorine content of leaves and appears to be a suitable fluorescence parameter in the future remote sensing of the physiological state of the vegetation by laser-equipped airborne systems.
Abstract: Using the two-wavelength chlorophyll fluorometer the fluorescence induction kinetics (Kautsky effect) were measured simultaneously in the 690 nm and 730 nm region for ten common tree species during the greening period (April to July). The chlorophyll-fluorescence ratio F690/F730 (i.e. ratio of fluorescence intensity at the two maxima near 690 and 730 nm) was calculated from the laser-induced induction kinetics (He/Ne-laser 632.8 nm) at the fluorescence maximum and the steady state. The ratio F690/F730 decreases with increasing chlorophyll content of developing leaves. Its dependence on the chlorophyll content can be fairly well expressed by a power function which has a general validity for leaves, pigment extracts and chloroplast suspensions. The ratio F690/F730 is somewhat higher at maximum (fm) than at steady-state fluorescence (fs), but there is a very good correlation between both values. The ratio F690/F730 is a good indicator of the chlorophyll content and can be used as a non-destructive measure of the chlorophyll content of leaves. It also appears to be a suitable fluorescence parameter in the future remote sensing of the physiological state of the vegetation by laser-equipped airborne systems.
11 Aug 1990
TL;DR: A solution against real time attacks in which active eavesdroppers relay questions and answers or the prover helps deliberately an impersonator is given and it is proved that the solution protects against the real-time attacks.
Abstract: Fiat and Shamir have proposed to use zero-knowledge interactive proofs to obtain secure identification mechanisms. Real time attacks in which active eavesdroppers relay questions and answers or in which the prover helps deliberately an impersonator have been described [4j. In this paper a solution against such frauds is given and (based on some physical assumptions) it is proved that the solution protects against the real-time attacks.
TL;DR: The approach uses a standardized, external format for graphs and handles extensions with program generator technology: the I/O routines for reading and writing extended node and edge data structures are produced automatically from the declarations of these data structures.
Abstract: EDGE is an editor kernel for the direct and visual manipulation of graphs. The kernel can be adapted quickly to diverse applications based on graphs, such as PERT chart editing, directory browsing, call graph display, logic circuit simulation or configuration visualization. EDGE provides potential solutions to the following general problems faced by any graph editor. (1) Automatic graph layout: how can application-specific layout requirements, individual preferences, and layout stability be integrated with automatic layout algorithms? EDGE solves this problem with a novel algorithm that is based on layout constraints. (2) Graph abstraction: how can users deal with large graphs containing hundreds of nodes and edges, and thousands of edge crossings? EDGE can reduce the apparent complexity with subgraph abstractions and a novel clustering technique called edge concentration. (3) Adaptability: how should the editor kernel be structured to be adaptable to various applications? EDGE uses a special graph representation language for specifying visual appearance and the inheritance mechanism of C++ to achieve extendibility. (4) Persistence of graphs: how can the graph structures produced by the editor be kept in long-term storage, especially if the node and edge data structures have been extended for a particular application? Our approach uses a standardized, external format for graphs and handles extensions with program generator technology: the I/O routines for reading and writing extended node and edge data structures are produced automatically from the declarations of these data structures. This paper describes EDGE and presents details of the above solutions.
23 Apr 1990
TL;DR: Whether the local gray value variation can be exploited in the temporal as well as in the spatial domain in order to achieve further improvements at discontinuities in the optical flow field associated with the image areas of moving objects in image sequences is studied.
Abstract: Recent experimental results by Schnorr 89 with an approach based on a simplified ‘oriented smoothness constraint’ show considerable improvement at expected discontinuities of the optical flow field. It thus appears justified to study whether the local gray value variation can be exploited in the temporal as well as in the spatial domain in order to achieve further improvements at discontinuities in the optical flow field associated with the image areas of moving objects in image sequences. An extension of the oriented smoothness constraint into the temporal domain is presented. In this context, a local estimation approach for the spatio-temporal partial derivatives of optical flow has been developed. This, in turn, is used to compare two approaches for the definition of optical flow.
TL;DR: In this article, the effects of energy supply in local supersonic flow over airfoils are investigated including a detailed analysis of the two-dimensional structure in the diabatic case.
Abstract: Steady two-dimensional flow of vapor/carrier gas mixtures (moist air) with nonequilibrium condensation is investigated in theory and experiment. Aside from Laval nozzles, transonic flow over airfoils at M