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  • 1
    Electronic Resource
    Electronic Resource
    Box schemes on quadrilateral meshes (1993)
    Springer
    Computing 51 (1993), S. 271-292 
    Details
    ISSN: 1436-5057
    Keywords: 65N15 ; 65N99 ; 35A40 ; Box method ; boundary value problem ; finite volume method ; variational formulation ; stability ; error bounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Box-Methoden (Finite-Volumen-Methoden) sind verbreitete Verfahren zur Lösung physikalischer Erhaltungsgleichungen, insbesondere in der Strömungsmechanik. In dieser Arbeit werden zwei Methoden für elliptische Differentialgleichungen untersucht, die Diagonal-Boxen und die Schwerpunkt-Boxen. Da die Box-Methoden im Sinne von Petrov-Galerkin-Verfahren interpretiert werden können, erhält man vergleichbar zur Finiten-Element-Methode eine variationsrechnerische Stabilitäts- und Fehleranalyse. Damit werdenO(h)- undO(h 2)-Fehlerabschätzungen hergeleitet. Lokale Eigenwertprobleme führen zu Stabilitätsaussagen. Allerdings ergibt sich eine Abhängigkeit von der Anzahl und Art gestörter Vierecke. Insbesondere die Diagonal-Boxen sind anfällig für lokale Störungen.
    Notes: Abstract Box schemes (finite volume methods) are widely used in fluiddynamics, especially for the solution of conservation laws. In this paper two box-schemes for elliptic equations are analysed with respect to quadrilateral meshes. Using a variational formulation, we gain stability theorems for two different box methods, namely the so-called diagonal boxes and the centre boxes. The analysis is based on an elementwise eigenvalue problem. Stability can only be guaranteed under additional assumptions on the geometry of the quadrilaterals. For the diagonal boxes unsuitable elements can lead to global instabilities. The centre boxes are more robust and differ not so much from the finite element approach. In the stable case, convergence results up to second order are proved with well-known techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02238536
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  • 2
    Electronic Resource
    Electronic Resource
    Vergleich der biologischen Aktivität und Stabilität von Menadion und Menadiol bei Hühnerküken (1990)
    Springer
    European journal of nutrition 29 (1990), S. 219-228 
    Details
    ISSN: 1436-6215
    Keywords: Vitamin K ; Menadion ; Menadiol ; Bioverfügbarkeit ; Stabilität ; Geflügel ; vitamin K ; menadione ; menadiol ; bioavailability ; stability ; poultry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary A bioassay of vitamin K is described, based on the prothrombin clotting time of 3-week-old, vitamin-K-depleted, and cumatetralyl-sensitized male broiler chicks, using a homologous thrombokinase preparation. With this test it could be shown that the diacetate and dibutyrate esters of menadiol are vitamin-K-active. The bioactivity of menadione from these menadiolesters amounted to about 70 % of the standard menadione from a coated menadione sodium bisulfite (Dohyfral). Menadiol seems to be temperature-resistant under such conditions, whereby two uncoated MSB preparations lost about 60 % of their activity.
    Notes: Zusammenfassung In einem biologischen Testverfahren an Cumatetralyl sensibilisierten Küken konnte in 3 Versuchen anhand des Parameters Thromboplastinzeit mit homologer Thrombokinase gezeigt werden, da\ Menadioldiacetat und Menadioldibutyrat Vitamin-K-wirksam sind. Die biologische Wirksamkeit von Menadion aus diesen Menadiolestern betrug ca. 70 % der Menadionaktivität aus gecoatetem Menadionbisulfit (Dohyfral®). Im Gegensatz zu 2 ungeschützten MSB-Präparationen, welche bei Wärmebelastung ca. 60 % ihrer ursprünglichen Wirkung verloren, waren die Menadiolester temperaturstabil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02023079
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  • 3
    Electronic Resource
    Electronic Resource
    A bifurcation analysis of the nonlinear parametric programming problem (1990)
    Springer
    Mathematical programming 47 (1990), S. 117-141 
    Details
    ISSN: 1436-4646
    Keywords: Bifurcation ; singularity ; parametric programming ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract The structure of solutions to the nonlinear parametric programming problem with a one dimensional parameter is analyzed in terms of the bifurcation behavior of the curves of critical points and the persistence of minima along these curves. Changes in the structure of the solution occur at singularities of a nonlinear system of equations motivated by the Fritz John first-order necessary conditions. It has been shown that these singularities may be completely partitioned into seven distinct classes based upon the violation of one or more of the following: a complementarity condition, a constraint qualification, and the nonsingularity of the Hessian of the Lagrangian on a tangent space. To apply classical bifurcation techniques to these singularities, a further subdivision of each case is necessary. The structure of curves of critical points near singularities of lowest (zero) codimension within each case is analyzed, as well as the persistence of minima along curves emanating from these singularities. Bifurcation behavior is also investigated or discussed for many of the subcases giving rise to a codimension one singularity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01580856
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  • 4
    Electronic Resource
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    Characterization of stable matchings as extreme points of a polytope (1992)
    Springer
    Mathematical programming 54 (1992), S. 57-67 
    Details
    ISSN: 1436-4646
    Keywords: Matchings ; stability ; extreme points ; polytope
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract The purpose of this paper is to extend a modified version of a recent result of Vande Vate (1989) which characterizes stable matchings as the extreme points of a certain polytope. Our proofs are simpler and more transparent than those of Vande Vate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01586041
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  • 5
    Electronic Resource
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    Quantitative stability of variational systems: III.ε-approximate solutions (1993)
    Springer
    Mathematical programming 61 (1993), S. 197-214 
    Details
    ISSN: 1436-4646
    Keywords: Epi-convergence ; epi-distance ; stability ; convex optimization ; approximate solutions ; subgradients ; level sets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We prove that theε-optimal solutions of convex optimization problems are Lipschitz continuous with respect to data perturbations when these are measured in terms of the epi-distance. A similar property is obtained for the distance between the level sets of extended real valued functions. We also show that these properties imply that theε-subgradient mapping is Lipschitz continuous.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01582147
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  • 6
    Electronic Resource
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    The spectral accuracy of a fully-discrete scheme for a nonlinear third order equation (1990)
    Springer
    Computing 44 (1990), S. 187-196 
    Details
    ISSN: 1436-5057
    Keywords: 65M10 ; Spectral method ; stability ; stability threshold
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Zur numerischen Lösung einer nichtlinearen Differentialgleichung dritter Ordnung, herrührend aus einem Strömungsproblem bei Gasteilchen, wird ein zeitdiskreter Pseudo-spektral-Algorithmus vorgeschlagen. Stabilität und Konvergenz des neuen Differenzenverfahrens werden analysiert. Numerische Vergleiche mit bestehenden Differenzenschemata sprechen klar zugunsten des neuen Verfahrens.
    Notes: Abstract A time-discrete pseudospectral algorithm is suggested for the numerical solution of a nonlinear third order equation arising in fluidization. The nonlinear stability and convergence of the new scheme are analyzed. Numerical comparisons with available finite-difference methods are also reported which clearly indicate the superiority of the new scheme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262215
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  • 7
    Electronic Resource
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    Stationary waiting time derivatives (1992)
    Springer
    Queueing systems 12 (1992), S. 369-389 
    Details
    ISSN: 1572-9443
    Keywords: Perturbation analysis ; stability ; stochastic difference equations ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract We investigate the stability of waiting-time derivatives when inputs to a queueing system-service times and interarrival times-depend on a parameter. We give conditions under which the sequence of waiting-time derivatives admits a stationary distribution, and under which the derivatives converge to the stationary regime from all initial conditions. Further hypotheses ensure that the expectation of a stationary waiting-time derivative is, in fact, the derivative of the expected stationary waiting time. This validates the use of simulation-based infinitesimal perturbation analysis estimates with a variety of queueing processes. We examine waiting-time sequences satisfying recursive equations. Our basic assumption is that the input and its derivatives are stationary and ergodic. Under monotonicity conditions, the method of Loynes establishes the convergence of the derivatives. Even without such conditions, the derivatives obey a linear difference equation with random coefficients, and we exploit this fact to find stability conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01158809
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  • 8
    Electronic Resource
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    Re-entrant lines (1993)
    Springer
    Queueing systems 13 (1993), S. 87-110 
    Details
    ISSN: 1572-9443
    Keywords: Manufacturing systems ; semiconductor manufacturing ; thin film lines ; re-entrant lines ; scheduling policies ; queueing networks ; buffer priority policies ; due date policies ; stability ; stochastic control ; mean delay ; variance of delay ; machine failures ; set-up times
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Traditionally, manufacturing systems have mainly been treated as either job shops or flow shops. In job shops, parts may arrive with random routes, with each route having a low volume. In flow shops, the routes are fixed and acyclic, as in assembly lines. With the advent of semiconductor manufacturing plants, and more recently, thin film lines, this dichotomy needs to be expanded to consider another class of systems, which we call “re-entrant lines”. The distinguishing feature of these manufacturing systems is that parts visit some machines more than once at different stages of processing. Scheduling problems arise because several parts at different stages of processing may be in contention with each other for service at the same machine. There may be uncertainties in the form of random service or set-up times, as well as random machine failures and repairs. The goal of scheduling is to improve performance measures such as mean sojourn time in the system, which is also known as the mean “cycle-time”, or the variance of the cycle-time. In this paper we provide a tutorial account of some recent results in this field. We describe several scheduling policies of interest, and provide some results concerning their stability and performance. Several open problems are suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01158930
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  • 9
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    On pathwise behavior of multiserver queues (1994)
    Springer
    Queueing systems 15 (1994), S. 279-288 
    Details
    ISSN: 1572-9443
    Keywords: Sample-path ; point processes ; workload ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In this paper, by exploiting recent results on the pathwise behavior of the workload process in single server, work conserving queues of theG/G/1/∞ type, we show that the workload of multiserver, work conserving queues ofG/G/m/∞ (m〈∞) (andG/G/∞) queues satisfies an o(t) growth condition, provided that the time average of the work brought into the system is less thanm form 〈 ∞ (and finite form=∞).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01189241
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  • 10
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    Stability and continuity of polling systems (1994)
    Springer
    Queueing systems 16 (1994), S. 115-137 
    Details
    ISSN: 1572-9443
    Keywords: Polling systems ; stability ; stochastic continuity ; general arrival process ; functional limit theorems.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract The stability of a polling system with exhaustive service and a finite number of users, each with infinite buffers is considered. The arrival process is more general than a Poisson process and the system is not slotted. Stochastic continuity of the stationary distributions, rates of convergence and functional limit theorems for the queue length and waiting time processes have also been proved. The results extend to the gated service discipline.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01158952
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  • 11
    Electronic Resource
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    Open queueing networks in discrete time-some limit theorems (1993)
    Springer
    Queueing systems 14 (1993), S. 159-175 
    Details
    ISSN: 1572-9443
    Keywords: Queueing networks ; nonproduct form networks ; stability ; stochastic continuity ; functional limit theorems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract A finite number of nodes, each with a single server and infinite buffers, is considered in discrete time. The service may be FIFO and the service times are constant. The external arrivals and the routing decision variables form a general stationary sequence. Stability of the system is proved under these assumptions. Extension to multiple servers at a node and general stationary distributions holds. If the external input is i.i.d. and the routing is Markovian then stochastic ordering, continuity of stationary distributions, rates of convergence, a functional CLT and a functional LIL and various other limit theorems for the queue length process are also proved. Generalizations to multiple servers at nodes, customers with priority, multiple customer classes, general service length and Markov modulated external arrival cases are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01153532
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  • 12
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    Monotonicity and stability of periodic polling models (1994)
    Springer
    Queueing systems 15 (1994), S. 211-238 
    Details
    ISSN: 1572-9443
    Keywords: polling system ; stability ; Markov chain ; stochastic monotonicity ; heavy traffic ; nonpreemptive local priority
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper deals with the stability of periodic polling models with a mixture of service policies. Customers arrive according to independent Poisson processes. The service times and the switchover times are independent with general distributions. The necessary and sufficient condition for the stability of such polling systems is established. The proof is based on the stochastic monotonicity of the state process at the polling instants. The stability of only a subset of the queues is also analyzed and, in case of heavy traffic, the order of explosion of the queues is given. The results are valid for a model with set-up times, and also when there is a local priority rule at the queues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01189238
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  • 13
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    Single-server queues with spatially distributed arrivals (1994)
    Springer
    Queueing systems 17 (1994), S. 317-345 
    Details
    ISSN: 1572-9443
    Keywords: Single-server queue ; spatially distributed arrival points ; travelling server ; Brownian motion ; embedded Markov chain ; stability ; Tweedie's lemma ; regenerative processes ; stochastic decomposition ; equilibrium equations ; mean queue length
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Consider a queueing system where customers arrive at a circle according to a homogeneous Poisson process. After choosing their positions on the circle, according to a uniform distribution, they wait for a single server who travels on the circle. The server's movement is modelled by a Brownian motion with drift. Whenever the server encounters a customer, he stops and serves this customer. The service times are independent, but arbitrarily distributed. The model generalizes the continuous cyclic polling system (the diffusion coefficient of the Brownian motion is zero in this case) and can be interpreted as a continuous version of a Markov polling system. Using Tweedie's lemma for positive recurrence of Markov chains with general state space, we show that the system is stable if and only if the traffic intensity is less than one. Moreover, we derive a stochastic decomposition result which leads to equilibrium equations for the stationary configuration of customers on the circle. Steady-state performance characteristics are determined, in particular the expected number of customers in the system as seen by a travelling server and at an arbitrary point in time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01158698
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  • 14
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    Stability of token passing rings (1992)
    Springer
    Queueing systems 11 (1992), S. 7-33 
    Details
    ISSN: 1572-9443
    Keywords: Token passing rings ; stability ; substability ; ergodicity ; Markov chains ; Loynes' scheme ; stochastically dominant ; Little's formula ; regenerative processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract A sufficient stability condition for the standard token passing ring has been “known” since the seminal paper by Kuehn in 1979. However, this condition was derived without formal proof, and the proof seems to be of considerable interest to the research community. In fact, Watson observed that in the performance evaluation of token passing rings, “it is convenient to derive stability conditions ... (without proof)”. Our intention is to fill this gap, and to provide a formal proof of thesufficient and necessary stability condition for the token passing ring. In this paper, we present the case when the arrival process to each queue is Poisson but service times and switchover times are generally distributed. We consider in depth a gatedl-limited (l≤ ∞) service discipline for each station. We also indicate that the basic steps of our technique can be used to study the stability of some other multiqueue systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01159285
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  • 15
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    Queues with service times and interarrival times depending linearly and randomly upon waiting times (1990)
    Springer
    Queueing systems 6 (1990), S. 335-351 
    Details
    ISSN: 1572-9443
    Keywords: State-dependent service and interarrival times ; Lindley equation ; recursive stochastic equations ; stability ; stochastic comparisons ; normal approximations ; scheduling arrivals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract We consider a modification of the standardG/G/1 queue with unlimited waiting space and the first-in first-out discipline in which the service times and interarrival times depend linearly and randomly on the waiting times. In this model the waiting times satisfy a modified version of the classical Lindley recursion. We determine when the waiting-time distributions converge to a proper limit and we develop approximations for this steady-state limit, primarily by applying previous results of Vervaat [21] and Brandt [4] for the unrestricted recursionY n+1=C n Y n +X n . Particularly appealing for applications is a normal approximation for the stationary waiting time distribution in the case when the queue only rarely becomes empty. We also consider the problem of scheduling successive interarrival times at arrival epochs, with the objective of achieving nearly maximal throughput with nearly bounded waiting times, while making the interarrival time sequence relatively smooth. We identify policies depending linearly and deterministically upon the work in the system which meet these objectives reasonably well; with these policies the waiting times are approximately contained in a specified interval a specified fraction of time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02411482
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  • 16
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    DNA in wheat seeds from European archaeological sites (1994)
    Springer
    Cellular and molecular life sciences 50 (1994), S. 571-575 
    Details
    ISSN: 1420-9071
    Keywords: Ancient DNA ; archaeobotany ; carbonized grain ; DNA sequences ; glutenin alleles ; seed proteins ; Triticum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have used hybridization analysis to detect ancient DNA in wheat seeds collected from three archaeological sites in Europe and the Middle East. One of these samples, carbonizedT. spelta dated to the first millennium BC, has yielded PCR products after amplification with primers directed at the leader regions of the HMW (high molecular weight) glutenin alleles. Sequences obtained from these products suggest that the DNA present in the Danebury seeds is chemically damaged, as expected for ancient DNA, and also indicate that it should be possible to study the genetic variability of archaeological wheat by ancient DNA analysis. Finally, we describe a PCR-based system that enables tetraploid and hexaploid wheats to be distinguished.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01921727
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  • 17
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    Robust pole assignment for incomplete nonlinear decoupling applied to robots (1990)
    Springer
    Journal of intelligent and robotic systems 3 (1990), S. 259-289 
    Details
    ISSN: 1573-0409
    Keywords: Nonlinear decoupling ; feedback linearization ; functional analysis ; elastic robots ; robustness ; stability ; pole assignment ; nonlinear systems ; robot control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A robustness analysis and synthesis for incomplete nonlinear decoupling for a class of nonlinear systems is discussed. Rigid and elastic-joint robot models belong to this class. For the elastic case, a transformation facilitates the robustness analysis under a weak assumption. Charts with H 1- and H ∞- norms of closed-loop disturbance transfer functions of the nonlinear-decoupled system are presented for a robust pole assignment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00126073
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  • 18
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    Real-time feedback scheduling of flexible manufacturing systems (1992)
    Springer
    Journal of intelligent and robotic systems 6 (1992), S. 51-63 
    Details
    ISSN: 1573-0409
    Keywords: Scheduling ; flexible manufacturing systems ; stability ; feedback
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A genetic manufacturing environment is considered. The emphasis is on small-lot, discrete, and asynchronous type of manufacturing systems rather than high volume and continuous type. Two classes of scheduling policies are proposed to render the machine stable. The policies are of feedback type. The decision is made in real-time and on-line.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314697
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  • 19
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    Force control of robots with nonlinearities (1992)
    Springer
    Journal of intelligent and robotic systems 6 (1992), S. 219-240 
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    ISSN: 1573-0409
    Keywords: Force control ; slip-stick friction ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper explores two practical issues related to the force control of manipulators. The first issue examined is how system stability is effected by commonly occurring manipulator nonlinearities, such as sampled-data, control signal saturation and slip-stick friction. It is shown that discretely implemented force control algorithms can drive the feedback force controlled manipulator into a limit cycle, even for a very small sampling period that by far satisfies Shannon's sampling theorem. The bounds of stability are enhanced by the presence of control signal saturation and slip stick friction. The second issue investigated is the inclusion of a high gain inner position loop as a means to minimize the unpredictability in the steady state error due to slip-stick friction. In order to support the theoretical conclusions, experiments were performed with the PUMP 560 industrial robot testbed facility developed at Colorado State University.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248017
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  • 20
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    Mycotoxin formation in HY-320 wheat during granary storage at 15 and 19% moisture content (1990)
    Springer
    Mycopathologia 111 (1990), S. 181-189 
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    ISSN: 1573-0832
    Keywords: mycotoxin ; ochratoxin ; Penicillium ; storage ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Eleven-kilogram parcels of HY-320 wheat, a cultivar of the new Canada Prairie Spring class, were kept at 15 and 19% initial moisture contents (IMC) in simulated storage in a Manitoba farm granary for 60 weeks to determine biotic and abiotic changes and mycotoxin production. Ochratoxin A reached a maximum of 0.24 ppm by week 20 in the 19% IMC wheat, but was absent in the 15% IMC wheat; no other mycotoxins were detected. Temperature, moisture content, O2 and CO2 levels, fat acidity values, seed germination, microfloral incidence and abundance, and the presence of other mycotoxins were monitored. Principal component analysis of all variables showed that the first principal components accounted for 32–41% of the system variability, and contained the ochratoxin A variable. Ochratoxin A was produced in moist grain that had decreased seed germination andAltermaria activity, and high fungal activity byPenicillium andAspergillus versicolor. Compared to other stored cereals previously studied, HY-320 wheat would be ranked in a low-risk category for mycotoxin formation, based on the ochratoxin A levels observed.
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    URL: http://dx.doi.org/10.1007/BF02282802
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  • 21
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    Effect of the incubation conditions on the production of patulin by Penicillium griseofulvum isolated from wheat (1991)
    Springer
    Mycopathologia 115 (1991), S. 163-168 
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    ISSN: 1573-0832
    Keywords: Penicillium griseofulvum ; patulin ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Sixty-four wheat samples from Spanish flour factories were screened for patulin and patulin-producing moulds. None of them was found to contain any patulin, whereas samples experimentally contaminated with this toxin proved it to be highly unstable. On the other hand, Penicillium griseofulvum was the only in vitro patulin-producing species found (19 samples). Mould growth in the samples was investigated by using yeast-sucrose medium (YES) and high-performance liquid chromatography (HPLC) to measure the amounts of toxin produced during 40 day's incubation at 20 and 28°C. The highest yield rate of patulin was obtained between the 20th and 30th day of incubation; such a rate, however, was very low throughout the vigorous growth phase, during the first 20 days of incubation. The more appropriate temperature for incubation and patulin production was 28 °C. We also investigated the influence of other incubation conditions in the yield and found stationary dark cultures to be more efficient that shaken or fermentation cultures in YES medium. The best patulin yield achieved was 11.9 mg in the culture broth and 6.3 mg in the mycelium from 100 ml of medium.
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    URL: http://dx.doi.org/10.1007/BF00462220
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  • 22
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    Effect of feeding cereal-legume diets to rats on in vitro absorption of45Ca (1990)
    Springer
    Cellular and molecular life sciences 46 (1990), S. 1016-1017 
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    ISSN: 1420-9071
    Keywords: In vitro absorption ; calcium ; wheat ; Bengal gram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The in vitro absorption of calcium from the duodenum was significantly less in a group of rats fed on a wheat diet than in a group fed a wheat and Bengal gram (70∶30) diet.
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    URL: http://dx.doi.org/10.1007/BF01940659
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  • 23
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    A reinforcement connectionist approach to robot path finding in non-maze-like environments (1992)
    Springer
    Machine learning 8 (1992), S. 363-395 
    Details
    ISSN: 0885-6125
    Keywords: Connectionism ; reinforcement learning ; robot path finding ; stability ; reactive systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper presents a reinforcement connectionist system which finds and learns the suitable situation-action rules so as to generate feasible paths for a point robot in a 2D environment with circular obstacles. The basic reinforcement algorithm is extended with a strategy for discovering stable solution paths. Equipped with this strategy and a powerful codification scheme, the path-finder (i) learns quickly, (ii) deals with continuous-valued inputs and outputs, (iii) exhibits good noise-tolerance and generalization capabilities, (iv) copes with dynamic environments, and (v) solves an instance of the path finding problem with strong performance demands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00992702
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  • 24
    Electronic Resource
    Electronic Resource
    A Reinforcement Connectionist Approach to Robot Path Finding in Non-Maze-Like Environments (1992)
    Springer
    Machine learning 8 (1992), S. 363-395 
    Details
    ISSN: 0885-6125
    Keywords: Connectionism ; reinforcement learning ; robot path finding ; stability ; reactive systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper presents a reinforcement connectionist system which finds and learns the suitable situation-action rules so as to generate feasible paths for a point robot in a 2D environment with circular obstacles. The basic reinforcement algorithm is extended with a strategy for discovering stable solution paths. Equipped with this strategy and a powerful codification scheme, the path-finder (i) learns quickly, (ii) deals with continuous-valued inputs and outputs, (iii) exhibits good noise-tolerance and generalization capabilities, (iv) copes with dynamic environments, and (v) solves an instance of the path finding problem with strong performance demands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022684924132
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  • 25
    Electronic Resource
    Electronic Resource
    DECUHR: an algorithm for automatic integration of singular functions over a hyperrectangular region (1994)
    Springer
    Numerical algorithms 8 (1994), S. 201-220 
    Details
    ISSN: 1572-9265
    Keywords: Automatic ; adaptive ; cubature ; singularity ; extrapolation ; stability ; 65D30 ; 65-04 ; 65B05
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We describe an automatic cubature algorithm for functions that have a singularity on the surface of the integration region. The algorithm combines an adaptive subdivision strategy with extrapolation. The extrapolation uses a non-uniform subdivision that can be directly incorporated into the subdivision strategy used for the adaptive algorithm. The algorithm is designed to integrate a vector function over ann-dimensional rectangular region and a FORTRAN implementation is included.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02142691
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  • 26
    Electronic Resource
    Electronic Resource
    Pharmaceutical development of a parenteral formulation of the novel anti-tumor agent carzelesin (U-80,244) (1994)
    Springer
    Investigational new drugs 12 (1994), S. 303-314 
    Details
    ISSN: 1573-0646
    Keywords: carzelesin (U-80,244) ; analytical characterization ; parenteral formulation ; stability ; degradation products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The aim of this study was to design a parenteral dosage form for the investigational cytotoxic drag carzelesin. A stable formulation in PET (Polyethylene glycol 400/absolute ethanol/Tween 80, 6:3:1, v/v/v) was developed. The prototype, containing 0.50 mg carzelesin in 2.0 ml PET formulation, was found to be the optimal formulation in terms of solubility, stability and dosage requirements in phase I clinical trials. Quality control of the formulation showed that the pharmaceutical preparation of carzelesin in PET is not negatively influenced by the manufacturing process. Shelf life studies demonstrated that the formulation is stable for at least 1 year, when stored at −30°C in the dark. In addition, the stability of carzelesin in the PET formulation is discussed as a function of temperature, additives and after dilution in infusion fluids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00873045
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  • 27
    Electronic Resource
    Electronic Resource
    A survey of the natural occurrence ofFusarium toxins in wheat grown ina southwestern area of Germany (1993)
    Springer
    Mycopathologia 121 (1993), S. 115-121 
    Details
    ISSN: 1573-0832
    Keywords: Fusarium toxins ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Wheat for feed use (84 samples) was collected after harvest from 79 farms in a southwestern part of Germany (Baden-Wuerttemberg). The 1987 crop year was characterized by heavy rainfall in the summer months. The internal mycoflora of wheat samples was primarily fusaria, and storage fungi were rarely present. TheFusarium toxins, zearalenone (ZON), α- and β-zearalenol (α,β-ZOL), deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-AcDON), nivalenol (NIV), T-2 Toxin (T-2), HT-2 toxin (HT-2) and diacetoxyscirpenol (DAS) were analysed by gas chromatography with mass selective detection (detection limit: 1–3 µg/kg). Each of the samples contained at least one of theFusarium toxins examined except DAS. DON, ZON, 3-AcDON, NIV, T-2, HT-2 and α-ZOL were detected in 96%, 80%, 59%, 26%, 26%, 7% and 5% of samples, with an average of 1632, 178, 7, 9, 82, 10 and 23 µg/kg, and a maximum of 20538, 8036, 18, 32, 249, 20 and 71 µg/kg, respectively. β-ZOL (12 µg/kg) was found in one sample with α-ZOL (71 µg/kg). One, two, three, four, five and sixFusarium toxins were detected in 6%, 27%, 37%, 23%, 4%, and 4% of total samples, respectively. The most frequent combination was that of ZON with DON and 3-AcDON, followed by the combinations ZON/DON and ZON/DON/3-AcDON/NIV in 22, 20, and 11% of total samples, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01103579
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