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1
Davison, J. L. „CONTINUED FRACTIONS WITH BOUNDED PARTIAL QUOTIENTS“. Proceedings of the Edinburgh Mathematical Society 45, Nr. 3 (Oktober 2002): 653–71. http://dx.doi.org/10.1017/s001309150000119x.
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AbstractPrecise bounds are given for the quantity$$ L(\alpha)=\frac{\limsup_{m\rightarrow\infty}(1/m)\ln q_m}{\liminf_{m\rightarrow\infty}(1/m)\ln q_m}, $$where $(q_m)$ is the classical sequence of denominators of convergents to the continued fraction $\alpha=[0,u_1,u_2,\dots]$ and $(u_m)$ is assumed bounded, with a distribution.If the infinite word $\bm{u}=u_1u_2\dots$ has arbitrarily large instances of segment repetition at or near the beginning of the word, then we quantify this property by means of a number $\gamma$, called the segment-repetition factor.If $\alpha$ is not a quadratic irrational, then we produce a specific sequence of quadratic irrational approximations to $\alpha$, the rate of convergence given in terms of $L$ and $\gamma$. As an application, we demonstrate the transcendence of some continued fractions, a typical one being of the form $[0,u_1,u_2,\dots]$ with $u_m=1+\lfloor m\theta\rfloor\Mod n$, $n\geq2$, and $\theta$ an irrational number which satisfies any of a given set of conditions.AMS 2000 Mathematics subject classification: Primary 11A55. Secondary 11B37
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Razgon, Igor. „On Oblivious Branching Programs with Bounded Repetition that Cannot Efficiently Compute CNFs of Bounded Treewidth“. Theory of Computing Systems 61, Nr. 3 (17.10.2016): 755–76. http://dx.doi.org/10.1007/s00224-016-9714-0.
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Asahiro, Yuichi, Jesper Jansson, Guohui Lin, Eiji Miyano, Hirotaka Ono und Tadatoshi Utashima. „Exact algorithms for the repetition-bounded longest common subsequence problem“. Theoretical Computer Science 838 (Oktober 2020): 238–49. http://dx.doi.org/10.1016/j.tcs.2020.07.042.
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4
Holub, Štěpán. „Words with unbounded periodicity complexity“. International Journal of Algebra and Computation 24, Nr. 06 (September 2014): 827–36. http://dx.doi.org/10.1142/s0218196714500362.
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If an infinite non-periodic word is uniformly recurrent or is of bounded repetition, then the limit of its periodicity complexity is infinity. Moreover, there are uniformly recurrent words with the periodicity complexity arbitrarily high at infinitely many positions.
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Serfes, Konstantinos, und Nicholas C. Yannelis. „LEARNING IN BAYESIAN GAMES BY BOUNDED RATIONAL PLAYERS II: NONMYOPIA“. Macroeconomic Dynamics 2, Nr. 2 (Juni 1998): 141–55. http://dx.doi.org/10.1017/s1365100598007019.
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We generalize results of earlier work on learning in Bayesian games by allowing players to make decisions in a nonmyopic fashion. In particular, we address the issue of nonmyopic Bayesian learning with an arbitrary number of bounded rational players, i.e., players who choose approximate best-response strategies for the entire horizon (rather than the current period). We show that, by repetition, nonmyopic bounded rational players can reach a limit full-information nonmyopic Bayesian Nash equilibrium (NBNE) strategy. The converse is also proved: Given a limit full-information NBNE strategy, one can find a sequence of nonmyopic bounded rational plays that converges to that strategy.
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Feng, Deren, Xiaojuan Xu, Jin Luo, Xiaolong Lee, Zhaohu Yao und Chengda Yu. „A High-Repetition-Rate Bounded-Wave EMP Simulator Based on Hydrogen Thyratron and Transmission Line Transformer“. IEEE Transactions on Plasma Science 40, Nr. 12 (Dezember 2012): 3499–507. http://dx.doi.org/10.1109/tps.2012.2222030.
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Hellman, Ziv, und Ron Peretz. „A Survey on Entropy and Economic Behaviour“. Entropy 22, Nr. 2 (29.01.2020): 157. http://dx.doi.org/10.3390/e22020157.
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Entropy plays a significant role in the study of games and economic behaviour in several ways. A decision maker faced with an n-fold repetition of a decision-making problem needs to apply strategies that become increasingly complex as n increases. When several players are involved in selecting strategies in interactive games, bounds on the memories and cognitive capacities of the players can affect possible outcomes. A player who can recall only the last k periods of history is said to have bounded recall of capacity k. We present here a brief survey of results of games played by players with different bounded recall capacities, in particular those indicating surprisingly strong relations between memory and entropy in the study of the min-max values of repeated games with bounded recall. In addition, we consider uses of entropy in measuring the value of information of noisy signal structures, also known as experiments. These are represented by stochastic matrices, with the rows representing states of the world and the columns possible signals. The classic ordering of experiments, due to David Blackwell and based on decision-making criteria, is a partial ordering, which has led to attempts to extend this ordering to a total ordering. If a decision maker has a prior distribution over the states, receipt of a signal yields a posterior. The difference between the entropy of a prior and the expected entropy of the set of possible posteriors has been proposed as a natural extension of the Blackwell ordering. We survey this alongside the theory of rational inattention, which posits that, since individuals have limited attention, they do not always follow every single piece of economic news in planning their economic behaviour. By modelling attention limits as finite channel capacity in the sense of Shannon, economists have developed a theory that explains a range of observed economic behavioural phenomena well.
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McMillan, Christian. „Jung and Deleuze: Enchanted Openings to the Other: A Philosophical Contribution“. International Journal of Jungian Studies 10, Nr. 3 (08.02.2018): 184–98. http://dx.doi.org/10.1080/19409052.2018.1505236.
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This paper draws from resources in the work of Deleuze to critically examine the notion of organicism and holistic relations that appear in historical forerunners that Jung identifies in his work on synchronicity. I interpret evidence in Jung’s comments on synchronicity that resonate with Deleuze’s interpretation of repetition and time and which challenge any straightforward foundationalist critique of Jung’s thought. A contention of the paper is that Jung and Deleuze envisage enchanted openings onto relations which are not constrained by the presupposition of a bounded whole, whether at the level of the macrocosm or the microcosm. Openings to these relations entail the potential for experimental transformation beyond sedentary habits of thought which are blocked by a disenchanting ‘image of thought’ that stands in need of critique. Other examples of enchanted openings in Jung’s work are signposted in an effort to counter their marginalisation in some post-Jungian critiques and to signal their potential value from a Deleuzian perspective.
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Gharibian, Sevag, Jamie Sikora und Sarvagya Upadhyay. „QMA variants with polynomially many provers“. Quantum Information and Computation 13, Nr. 1&2 (Januar 2013): 135–57. http://dx.doi.org/10.26421/qic13.1-2-8.
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We study three variants of multi-prover quantum Merlin-Arthur proof systems. We first show that the class of problems that can be efficiently verified using polynomially many quantum proofs, each of logarithmic-size, is exactly \class{MQA} (also known as QCMA), the class of problems which can be efficiently verified via a classical proof and a quantum verifier. We then study the class $\class{BellQMA}(\poly)$, characterized by a verifier who first applies unentangled, nonadaptive measurements to each of the polynomially many proofs, followed by an arbitrary but efficient quantum verification circuit on the resulting measurement outcomes. We show that if the number of outcomes per nonadaptive measurement is a polynomially-bounded function, then the expressive power of the proof system is exactly \class{QMA}. Finally, we study a class equivalent to \class{QMA}($m$), denoted $\class{SepQMA}(m)$, where the verifier's measurement operator corresponding to outcome {\it accept} is a fully separable operator across the $m$ quantum proofs. Using cone programming duality, we give an alternate proof of a result of Harrow and Montanaro [FOCS, pp. 633--642 (2010)] that shows a perfect parallel repetition theorem for $\class{SepQMA}(m)$ for any $m$.
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Narmour, Eugene. „Music Expectation by Cognitive Rule-Mapping“. Music Perception 17, Nr. 3 (2000): 329–98. http://dx.doi.org/10.2307/40285821.
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Iterative rules appear everywhere in music cognition, creating strong expectations. Consequently, denial of rule projection becomes an important compositional strategy, generating numerous possibilities for musical affect. Other rules enter the musical aesthetic through reflexive game playing. Still other kinds are completely constructivist in nature and may be uncongenial to cognition, requiring much training to be recognized, if at all. Cognitive rules are frequently found in contexts of varied repetition (AA), but they are not necessarily bounded by stylistic similarity. Indeed, rules may be especially relevant in the processing of unfamiliar contexts (AB), where only abstract coding is available. There are many kinds of deduction in music cognition. Typical examples include melodic sequence, partial melodic sequence, and alternating melodic sequence (which produces streaming). These types may coexist in the musical fabric, involving the invocation of both simultaneous and nested rules. Intervallic expansion and reduction in melody also involve higherorder abstractions. Various mirrored forms in music entail rule-mapping as well, although these may be more difficult to perceive than their analogous visual symmetries. Listeners can likewise deduce additivity and subtractivity at work in harmony, tempo, texture, pace, and dynamics. Rhythmic augmentation and diminution, by contrast, rely on multiplication and division. The examples suggest numerous hypotheses for experimental research.
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Briet, Jop, Harry Buhrman, Troy Lee und Thomas Vidick. „Multipartite entanglement in XOR games“. Quantum Information and Computation 13, Nr. 3&4 (März 2013): 334–60. http://dx.doi.org/10.26421/qic13.3-4-11.
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We study multipartite entanglement in the context of XOR games. In particular, we study the ratio of the entangled and classical \emph{biases}, which measure the maximum advantage of a quantum or classical strategy over a uniformly random strategy. For the case of two-player XOR games, Tsirelson proved that this ratio is upper bounded by the celebrated Grothendieck constant. In contrast, \PG proved the existence of entangled states that give quantum players an unbounded advantage over classical players in a three-player XOR game. We show that the multipartite entangled states that are most often seen in today's literature can only lead to a bias that is a constant factor larger than the classical bias. These states include GHZ states, any state local-unitarily equivalent to combinations of GHZ and maximally entangled states shared between different subsets of the players (e.g., stabilizer states), as well as generalizations of GHZ states of the form $\sum_i \alpha_i \ket{i}\cdots\ket{i}$ for arbitrary amplitudes $\alpha_i$. Our results have the following surprising consequence: \emph{classical} three-player XOR games do not follow an XOR parallel repetition theorem, even a very weak one. Besides this, we discuss implications of our results for communication complexity and hardness of approximation. Our proofs are based on novel applications of extensions of Grothendieck's inequality, due to Blei and Tonge, and Carne, generalizing Tsirelson's use of Grothendieck's inequality to bound the bias of two-player XOR games.
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Cockett, J. Robin B., Jalel Zrida und J. Douglas Birdwell. „Stochastic Decision Theory“. Probability in the Engineering and Informational Sciences 3, Nr. 1 (Januar 1989): 13–54. http://dx.doi.org/10.1017/s0269964800000966.
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The manipulations and basic results of stochastic decision theory are introduced. The manipulations of idempotence, transposition, and repetition, introduced for deterministic decision trees, can be used to manipulate stochastic trees. However, there are two major differences. First, in order to obtain a complete set of manipulations it is necessary to introduce an additional rule called indifference. Second, these identities must be treated as rules of inference. Not all the rules can be soundly applied in both directions; in particular, idempotence is a one-way rule.A manipulation of a stochastic decision tree not only alters the structure of the tree, but also the probability distributions associated with the tree. This allows probability calculation to be viewed as structural manipulation. In particular, a retrieval corresponds to a conditional probability calculation. The algorithm for doing this calculation has, therefore, many applications. For example, the solution to the classical state-estimation problem and the retrieval of information from probabilistic or uncertain knowledge bases may both be viewed as an application of this algorithm.The main result of this paper is that these manipulations are complete and sound. In order to prove this result, it is necessary to have a semantic setting for these theories. The setting chosen is the category of description spaces which is a generalization of the category of bounded measure spaces with maps which do not increase measure. The proof of this result exploits the retrieval properties of stochastic terms and its relationship to conditional probability calculations in the models.
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Happel, Dieter, Bernhard Keller und Idun Reiten. „Bounded derived categories and repetitive algebras“. Journal of Algebra 319, Nr. 4 (Februar 2008): 1611–35. http://dx.doi.org/10.1016/j.jalgebra.2007.10.001.
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Černý, Anton. „On a class of infinite words with bounded repetitions“. RAIRO. Informatique théorique 19, Nr. 4 (1985): 337–49. http://dx.doi.org/10.1051/ita/1985190403371.
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Mueller, W., J. A. Donaldson, D. Dufresne und M. Rocheleau. „The Duparquet Formation: sedimentation in a late Archean successor basin, Abitibi greenstone belt, Quebec, Canada“. Canadian Journal of Earth Sciences 28, Nr. 9 (01.09.1991): 1394–406. http://dx.doi.org/10.1139/e91-123.
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In the south-central part of the Abitibi greenstone belt, a succession of Archean epiclastic sediments at least 2 km thick was deposited in the Duparquet Basin. The Destor–Porcupine fault and a secondary fault that splays off the major fault define the margins of this basin, which is at least 15 km long and up to 2.5 km wide. Sedimentary evidence of tectonic influence includes (i) rapid vertical and lateral facies changes over tens of metres; (ii) cyclic repetition of facies associations; (iii) mixed fining-upward – coarsening-upward – fining-upward sequences in conglomerate units; (iv) local derivation of most clasts; and (v) asymmetric distribution of fan deltas and braid deltas along the strike of the fault-bounded basin. Three basic facies associations are recognized: (i) conglomerate–sandstone facies association (CSFA); (ii) sandstone–argillite facies association (SAFA); and (iii) argillite–sandstone facies association (ASFA). The CSFA, which predominates at the faulted basin margins, constitutes 60–70% of the basin sediments. It exhibits salient features of streamflow-dominated fans or fan deltas, proximal braid deltas, and (or) coarse clastic braidplains. Large angular clasts of local derivation near the basin margins reflect limited distances of transport, supporting the alluvial fan – fan delta interpretation. The SAFA is assigned to a subaerial to subaqueous fan delta – braid delta setting, in part deposited during episodic storms and floods. The ASFA for the most part records sedimentation in a calm aqueous environment in which suspension deposition prevailed; a lacustrine setting is inferred, but incised conglomerates and channel-fill sandstones attest to sporadic floods and (or) storms. The CSFA in places occupies channels in the ASFA, suggesting progradation of alluvial fans into shallow water in response to source-area uplift. Modern analogues of the Duparquet Basin occur at convergent plate margins. Because it developed during a late orogenic stage, the Duparquet Basin may be classified as a successor basin. Sedimentary facies organization and basin configuration are similar to successor basins of the Cordillera of western Canada, as well as pull-apart basins adjacent to the San Andreas fault in California and the East Anatolian fault in Turkey.
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Wehner, Stephan. „On recursive enumerability with finite repetitions“. Journal of Symbolic Logic 64, Nr. 3 (September 1999): 927–45. http://dx.doi.org/10.2307/2586612.
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AbstractIt is an open problem within the study of recursively enumerable classes of recursively enumerable sets to characterize those recursively enumerable classes which can be recursively enumerated without repetitions. This paper is concerned with a weaker property of r.e. classes, namely that of being recursively enumerable with at most finite repetitions.This property is shown to behave more naturally: First we prove an extension theorem for classes satisfying this property. Then the analogous theorem for the property of recursively enumerable classes of being recursively enumerable with a bounded number of repetitions is shown not to hold. The index set of the property of recursively enumerable classes “having an enumeration with finite repetitions” is shown to be -complete.
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ALISTE-PRIETO, JOSÉ, und DANIEL CORONEL. „Tower systems for linearly repetitive Delone sets“. Ergodic Theory and Dynamical Systems 31, Nr. 6 (23.11.2010): 1595–618. http://dx.doi.org/10.1017/s0143385710000507.
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AbstractIn this paper we study linearly repetitive Delone sets and prove, following the work of Bellissard, Benedetti and Gambaudo, that the hull of a linearly repetitive Delone set admits a properly nested sequence of box decompositions (tower system) with strictly positive and uniformly bounded (in size and norm) transition matrices. This generalizes a result of Durand for linearly recurrent symbolic systems. Furthermore, we apply this result to give a new proof of a classic estimation of Lagarias and Pleasants on the rate of convergence of patch frequencies.
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LAMBERTI, LISA. „REPETITIVE HIGHER CLUSTER CATEGORIES OF TYPE An“. Journal of Algebra and Its Applications 13, Nr. 02 (10.10.2013): 1350091. http://dx.doi.org/10.1142/s0219498813500916.
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We show that the repetitive higher cluster category of type An, defined as the orbit category [Formula: see text], is equivalent to a category defined on a subset of diagonals in a regular polygon. This generalizes the construction of Caldero–Chapoton–Schiffler [Quivers with relations arising from clusters (An case), Trans. Amer. Math. Soc.358(3) (2006) 1347–1364], which we recover when p = m = 1, and the work of Baur–Marsh, [A geometric description of the m-cluster categories, Trans. Amer. Math. Soc.360(11) (2008) 5789–5803], treating the case p = 1, m > 1. Our approach also leads to a geometric model of the bounded derived category in type A.
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Wang, Ying-Chung, Chiang-Ju Chien und Chi-Nan Chuang. „ADAPTIVE ITERATIVE LEARNING CONTROL OF ROBOTIC SYSTEMS USING BACKSTEPPING DESIGN“. Transactions of the Canadian Society for Mechanical Engineering 37, Nr. 3 (September 2013): 591–601. http://dx.doi.org/10.1139/tcsme-2013-0047.
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In this paper, a backstepping adaptive iterative learning control (AILC) is proposed for robotic systems with repetitive tasks. The AILC is designed to approximate unknown certainty equivalent controller. Finally, we apply a Lyapunov like analysis to show that all adjustable parameters and the internal signals remain bounded for all iterations.
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Pogorzały, Zygmunt. „On locally bounded categories stably equivalent to the repetitive algebras of tubular algebras“. Colloquium Mathematicum 72, Nr. 1 (1997): 123–46. http://dx.doi.org/10.4064/cm-72-1-123-146.
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Wang, Ying Chung, Chiang Ju Chien und Chi Nan Chuang. „Backstepping Adaptive Iterative Learning Control for Robotic Systems“. Applied Mechanics and Materials 284-287 (Januar 2013): 1759–63. http://dx.doi.org/10.4028/www.scientific.net/amm.284-287.1759.
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A backstepping adaptive iterative learning control for robotic systems with repetitive tasks is proposed in this paper. The backstepping-like procedure is introduced to design the AILC. A fuzzy neural network is applied for compensation of the unknown certainty equivalent controller. Using a Lyapunov like analysis, we show that the adjustable parameters and internal signals remain bounded, the tracking error will asymptotically converge to zero as iteration goes to infinity.
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Wang, Lei, Mu Li und Huizhong Yang. „Robust PD-Type Iterative Learning Control of Discrete Linear Repetitive Processes in the Finite Frequency Domain“. Mathematics 8, Nr. 6 (18.06.2020): 1004. http://dx.doi.org/10.3390/math8061004.
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This paper studies a robust iterative learning control design for discrete linear repetitive processes in the finite frequency domain. Firstly, the state-space model of the iterative learning process is deduced. Then the dynamic performance condition of the control system in the finite frequency domain is derived by combining it with the stability theory of discrete linear repetitive processes. The system performances in the finite frequency domain are then transformed into the corresponding solutions of the linear matrix inequality by using the generalised KYP lemma. Finally, an integrated state feedback PD-type iterative learning control strategy is proposed. The robust control problem with norm-bounded uncertainty and convex polyhedral uncertainty are also considered in this paper. The simulation of the injection velocity in injection molding verified that the proposed methods in this paper are more effective than the P-type state feedback iterative learning control algorithm.
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Chen, Wentao, Yechun Lin und Qingping Wu. „State Feedback Guaranteed Cost Repetitive Control for Uncertain Discrete-Time Systems“. Mathematical Problems in Engineering 2011 (2011): 1–16. http://dx.doi.org/10.1155/2011/904914.
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This paper considers the problem of guaranteed cost repetitive control for uncertain discrete-time systems. The uncertainty in the system is assumed to be norm-bounded and time-varying. The objective is to develop a novel design method so that the closed-loop repetitive control system is quadratically stable and a certain bound of performance index is guaranteed for all admissible uncertainties. The state feedback control technique is used in the paper. While for the case that the states are not measurable, an observer-based control scheme is adopted. Sufficient conditions for the existence of guaranteed cost control law are derived in terms of linear matrix inequality (LMI). The control and observer gains are characterized by the feasible solutions to these LMIs. The optimal guaranteed cost control law is obtained efficiently by solving an optimization problem with LMI constraints using existing convex optimization algorithms. A simulation example is provided to illustrate the validity of the proposed method.
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Neumann, Peter M., und Cheryl E. Praeger. „On Tensor-Factorisation Problems,I: The Combinatorial Problem“. LMS Journal of Computation and Mathematics 7 (2004): 73–100. http://dx.doi.org/10.1112/s1461157000001054.
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AbstractA k-multiset is an unordered k-tuple, perhaps with repetitions. If x is an r-multiset {x1, …, xr} and y is an s-multiset {y1, …, ys} with elements from an abelian group A the tensor product x ⊗ y is defined as the rs-multiset {xi yj | 1 ≤ i ≤ r, 1 ≤ j ≤ s}. The main focus of this paper is a polynomial-time algorithm to discover whether a given rs-multiset from A can be factorised. The algorithm is not guaranteed to succeed, but there is an acceptably small upper bound for the probability of failure. The paper also contains a description of the context of this factorisation problem, and the beginnings of an attack on the following division-problem: is a given rs-multiset divisible by a given r-multiset, and if so, how can division be achieved in polynomially bounded time?
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Moore, J. B., R. Horowitz und W. Messner. „Functional Persistence of Excitation and Observability for Learning Control Systems“. Journal of Dynamic Systems, Measurement, and Control 114, Nr. 3 (01.09.1992): 500–507. http://dx.doi.org/10.1115/1.2897375.
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Adaptive systems involving function learning can be formulated in terms of integral equations of the first kind, possibly with separable, finite-dimensional kernels. The learning process involves estimating the influence functions (Messner et al., 1989). To achieve convergence of the influence function estimates and exponentially stability, it is important to have persistence of excitation in the training tasks. This paper develops the concept of functional persistence of excitation (PE), and the associated concept of functional uniform complete observability (UCO). Relevant PE and UCO properties for linear systems are developed. For example, a key result is that uniform complete observability in this context is maintained under bounded integral operator output injection—a natural generalization of the corresponding finite dimensional result. This paper also demonstrates the application of the theory to linear error equations associated with a repetitive control algorithm.
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Chen, Chih-Cheng, Kelsen Serra, Albert C. Reynolds und Rajagopal Raghavan. „Pressure Transient Analysis Methods for Bounded Naturally Fractured Reservoirs“. Society of Petroleum Engineers Journal 25, Nr. 03 (01.06.1985): 451–64. http://dx.doi.org/10.2118/11243-pa.
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Abstract New methods for analyzing drawdown and buildup pressure data obtained at a well located in an infinite, pressure data obtained at a well located in an infinite, naturally fractured reservoir were presented recently. In this work, the analysis of both drawdown and buildup data in a bounded, naturally fractured reservoir is considered. For the bounded case, we show that five possible flow regimes may be exhibited by drawdown data. We delineate the conditions under which each of these five flow regimes exists and the information that can be obtained from each possible combination of flow regimes. Conditions under which semilog methods can be used to analyze buildup data are discussed for the bounded fractured reservoir case. New Matthews-Brons-Hazebroek (MBH) functions for computing the average reservoir pressure from buildup data are presented. pressure from buildup data are presented. Introduction This work considers the analysis of pressure data obtained at a well located at the center of a cylindrical, bounded, naturally fractured reservoir of uniform thickness. As is typical, a naturally fractured reservoir indicates a reservoir system in which the conductive properties of the rock are mainly due to the fracture system, and the rock matrix provides most of the storage capacity of the system. Several models of naturally fractured reservoirs have been presented m the literature. Warren and Root and Odeh presented m the literature. Warren and Root and Odeh assume "pseudosteady-state flow" in the matrix, whereas Kazemi, deSwaan, Najurieta, and Kucuk and Sawyers assume unsteady-state flow. The model used in this study is identical to the one considered in Refs. 4, 5, 7, and 8; however, these works considered only infinite-acting reservoirs. To our knowledge, the behavior of wells in bounded, naturally fractured reservoirs with unsteady-state flow in the matrix system has not been examined until now. This work considers the analysis of constant-rate production and buildup pressure data in a bounded, naturally production and buildup pressure data in a bounded, naturally fractured reservoir. For a bounded reservoir, we show that there are five distinct, useful flow regimes that may be exhibited by drawdown data. Flow Regimes 1, 2, and 11 are identical to the flow regimes identified in Refs. 7 and 8. During each of these three flow regimes, a semilog plot of the dimensionless wellbore pressure drop vs. plot of the dimensionless wellbore pressure drop vs. dimensionless time exhibits a straight line. The information that can be obtained from the various possible combinations of Flow Regimes 1 through 3 is discussed in Refs. 7 and 8. Flow Regime 5 corresponds to pseudo-steady-state flow. Flow Regime 4 denotes a flow pseudo-steady-state flow. Flow Regime 4 denotes a flow period during which a Cartesian graph of the dimensionless period during which a Cartesian graph of the dimensionless wellbore pressure drop vs. the square root of dimensionless time will be a straight line. In this work, we first establish the conditions under which each of the flow regimes exists. In particular, we show that Flow Regime 3 does not exist unless either the drainage radius or the dimensionless fracture transfer coefficient is large. Second, we show that useful information can be obtained from drawdown pressure data that reflect Flow Regime 4. Third, we delineate conditions that ensure that the methods of Refs. 7, and 8 can be used to analyze buildup data. Finally, we present new MBH functions for computing the average reservoir pressure in a naturally fractured reservoir. Mathematical Model We consider laminar flow of a slightly compressible, single-phase fluid of constant viscosity in an isotropic, cylindrical, naturally fractured reservoir of uniform thickness. Gravitational forces are negligible. The top, bottom, and outer reservoir boundaries are closed. A well located at the center of the cylinder is produced at a constant rate and then shut in to obtain buildup data. Initially, the pressure is uniform throughout the reservoir. We assume that all production is by way of the fracture system and that we have one-dimensional (ID), unsteady-state flow in the matrix. The matrix structure consists of "rectangular slabs"; that is, the matrix is divided by a set of parallel horizontal fractures. A schematic of the reservoir geometry is shown in Fig. 1. We consider an infinitesimally thin skin and neglect wellbore storage effects. The properties of both the matrix and fracture systems are assumed to be constant. Thus, our current model is identical to the one considered in Ref. 7 except that here the reservoir is assumed to be bounded. Because of symmetry, the mathematical problem can be formulated by considering only the repetitive element of Fig. 1. SPEJ p. 451
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Cook, D. J., und L. B. Holder. „Substructure Discovery Using Minimum Description Length and Background Knowledge“. Journal of Artificial Intelligence Research 1 (01.02.1994): 231–55. http://dx.doi.org/10.1613/jair.43.
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The ability to identify interesting and repetitive substructures is an essential component to discovering knowledge in structural data. We describe a new version of our SUBDUE substructure discovery system based on the minimum description length principle. The SUBDUE system discovers substructures that compress the original data and represent structural concepts in the data. By replacing previously-discovered substructures in the data, multiple passes of SUBDUE produce a hierarchical description of the structural regularities in the data. SUBDUE uses a computationally-bounded inexact graph match that identifies similar, but not identical, instances of a substructure and finds an approximate measure of closeness of two substructures when under computational constraints. In addition to the minimum description length principle, other background knowledge can be used by SUBDUE to guide the search towards more appropriate substructures. Experiments in a variety of domains demonstrate SUBDUE's ability to find substructures capable of compressing the original data and to discover structural concepts important to the domain. Description of Online Appendix: This is a compressed tar file containing the SUBDUE discovery system, written in C. The program accepts as input databases represented in graph form, and will output discovered substructures with their corresponding value.
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Gurtuev, Alim, und Zaur Ivanov. „Comparison of different land distribution mechanisms for a land-hungry region“. E3S Web of Conferences 164 (2020): 07017. http://dx.doi.org/10.1051/e3sconf/202016407017.
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This paper proposes an approach to the development an efficient land distribution mechanism for a particular land-hungry region. We separate budgetary and allocative efficiency and use general utility approach during evaluation of particular distribution mechanisms. We propose a model of potential land users, which allows quantifying the efficiency of a number of mechanisms of land distribution for land-hungry regions. Land users are represented as economic agents with bounded rationality and subjective utility functions. The model calculates allocation efficiency and budgetary efficiency as independent values and thus is more precise. It also has considerable flexibility and can be adjusted to specific agricultural technology and soil types. An analysis of the efficiency of various mechanisms for the test region showed that lottery mechanisms leads to losses of allocative efficiency compared with auction mechanisms. As for the budget revenues, the use of lottery mechanisms leads to much smaller losses of budgetary efficiency in comparison with simultaneous closed auctions of the first and second prices. But of all the mechanisms considered in the paper, the repetitive Vickrey auction leads to the smallest losses of budget efficiency in the model.
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Pacheco-Valencia, Víctor, José Alberto Hernández, José María Sigarreta und Nodari Vakhania. „Simple Constructive, Insertion, and Improvement Heuristics Based on the Girding Polygon for the Euclidean Traveling Salesman Problem“. Algorithms 13, Nr. 1 (21.12.2019): 5. http://dx.doi.org/10.3390/a13010005.
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The Traveling Salesman Problem (TSP) aims at finding the shortest trip for a salesman, who has to visit each of the locations from a given set exactly once, starting and ending at the same location. Here, we consider the Euclidean version of the problem, in which the locations are points in the two-dimensional Euclidean space and the distances are correspondingly Euclidean distances. We propose simple, fast, and easily implementable heuristics that work well, in practice, for large real-life problem instances. The algorithm works on three phases, the constructive, the insertion, and the improvement phases. The first two phases run in time O ( n 2 ) and the number of repetitions in the improvement phase, in practice, is bounded by a small constant. We have tested the practical behavior of our heuristics on the available benchmark problem instances. The approximation provided by our algorithm for the tested benchmark problem instances did not beat best known results. At the same time, comparing the CPU time used by our algorithm with that of the earlier known ones, in about 92% of the cases our algorithm has required less computational time. Our algorithm is also memory efficient: for the largest tested problem instance with 744,710 cities, it has used about 50 MiB, whereas the average memory usage for the remained 217 instances was 1.6 MiB.
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Felber, F. S., F. J. Wessel, N. C. Wild, H. U. Rahman, A. Fisher, C. M. Fowler, M. A. Liberman und A. L. Velikovich. „Gas–puff Z pinches with strong axial magnetic fields“. Laser and Particle Beams 5, Nr. 4 (November 1987): 699–706. http://dx.doi.org/10.1017/s0263034600003219.
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Ultrahigh axial magnetic fields have been compressed and measured in a gas-puff Z pinch. A 0·5-MA, 2–cm-radius annular gas-puff Z pinch with a 3-minute repetition rate was imploded radially onto an axial seed field, causing the field to compress. Axial magnetic field compressions up to 180 and peak magnetic fields up to 1·6 MG were measured. Faraday rotation of an argon laser (515·4 nm) in a quartz fiber on axis was the principal magnetic field diagnostic. Other diagnostics included a nitrogen laser interferometer, x-ray diodes, and magnetic field probes.The magnetic field compression results are consistent with simple snowplow and self-similar analytic models, which are presented. The axial magnetic fields strongly affect the Z pinch dynamics. Even small axial fields help stabilize the pinches, some of which exhibit several stable radial bounces during a current pulse.The method of compressing axial fields in a gas-puff Z pinch is extrapolable to the order of 100 MG. Scaling laws are presented. Potential applications of ultrahigh axial fields in Z pinches are discussed for x-ray lasers, inertial confinement fusion, and collimated sources of gamma radiation.
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Liu, Ruoyu, Kun Wang, Jun Liu, Wenjie Xu, Yang Zhou, Chenglong Zhu, Baosheng Wu et al. „De Novo Genome Assembly of Limpet Bathyacmaea lactea (Gastropoda: Pectinodontidae): The First Reference Genome of a Deep-Sea Gastropod Endemic to Cold Seeps“. Genome Biology and Evolution 12, Nr. 6 (28.05.2020): 905–10. http://dx.doi.org/10.1093/gbe/evaa100.
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Abstract Cold seeps, characterized by the methane, hydrogen sulfide, and other hydrocarbon chemicals, foster one of the most widespread chemosynthetic ecosystems in deep sea that are densely populated by specialized benthos. However, scarce genomic resources severely limit our knowledge about the origin and adaptation of life in this unique ecosystem. Here, we present a genome of a deep-sea limpet Bathyacmaea lactea, a common species associated with the dominant mussel beds in cold seeps. We yielded 54.6 gigabases (Gb) of Nanopore reads and 77.9-Gb BGI-seq raw reads, respectively. Assembly harvested a 754.3-Mb genome for B. lactea, with 3,720 contigs and a contig N50 of 1.57 Mb, covering 94.3% of metazoan Benchmarking Universal Single-Copy Orthologs. In total, 23,574 protein-coding genes and 463.4 Mb of repetitive elements were identified. We analyzed the phylogenetic position, substitution rate, demographic history, and TE activity of B. lactea. We also identified 80 expanded gene families and 87 rapidly evolving Gene Ontology categories in the B. lactea genome. Many of these genes were associated with heterocyclic compound metabolism, membrane-bounded organelle, metal ion binding, and nitrogen and phosphorus metabolism. The high-quality assembly and in-depth characterization suggest the B. lactea genome will serve as an essential resource for understanding the origin and adaptation of life in the cold seeps.
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Gotti, Marly. „On the local k-elasticities of Puiseux monoids“. International Journal of Algebra and Computation 29, Nr. 01 (Februar 2019): 147–58. http://dx.doi.org/10.1142/s0218196718500662.
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If [Formula: see text] is an atomic monoid and [Formula: see text] is a nonzero non-unit element of [Formula: see text], then the set of lengths [Formula: see text] of [Formula: see text] is the set of all possible lengths of factorizations of [Formula: see text], where the length of a factorization is the number of irreducible factors (counting repetitions). In a recent paper, F. Gotti and C. O’Neil studied the sets of elasticities [Formula: see text] of Puiseux monoids [Formula: see text]. Here, we take this study a step further and explore the local [Formula: see text]-elasticities of the same class of monoids. We find conditions under which Puiseux monoids have all their local elasticities finite as well as conditions under which they have infinite local [Formula: see text]-elasticities for sufficiently large [Formula: see text]. Finally, we focus our study of the [Formula: see text]-elasticities on the class of primary Puiseux monoids, proving that they have finite local [Formula: see text]-elasticities if either they are boundedly generated and do not have any stable atoms or if they do not contain [Formula: see text] as a limit point.
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Tawk, Lina, Gaëtan Chicanne, Jean-François Dubremetz, Véronique Richard, Bernard Payrastre, Henri J. Vial, Christian Roy und Kai Wengelnik. „Phosphatidylinositol 3-Phosphate, an Essential Lipid in Plasmodium, Localizes to the Food Vacuole Membrane and the Apicoplast“. Eukaryotic Cell 9, Nr. 10 (13.08.2010): 1519–30. http://dx.doi.org/10.1128/ec.00124-10.
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ABSTRACT Phosphoinositides are important regulators of diverse cellular functions, and phosphatidylinositol 3-monophosphate (PI3P) is a key element in vesicular trafficking processes. During its intraerythrocytic development, the malaria parasite Plasmodium falciparum establishes a sophisticated but poorly characterized protein and lipid trafficking system. Here we established the detailed phosphoinositide profile of P. falciparum-infected erythrocytes and found abundant amounts of PI3P, while phosphatidylinositol 3,5-bisphosphate was not detected. PI3P production was parasite dependent, sensitive to a phosphatidylinositol-3-kinase (PI3-kinase) inhibitor, and predominant in late parasite stages. The Plasmodium genome encodes a class III PI3-kinase of unusual size, containing large insertions and several repetitive sequence motifs. The gene could not be deleted in Plasmodium berghei, and in vitro growth of P. falciparum was sensitive to a PI3-kinase inhibitor, indicating that PI3-kinase is essential in Plasmodium blood stages. For intraparasitic PI3P localization, transgenic P. falciparum that expressed a PI3P-specific fluorescent probe was generated. Fluorescence was associated mainly with the membrane of the food vacuole and with the apicoplast, a four-membrane bounded plastid-like organelle derived from an ancestral secondary endosymbiosis event. Electron microscopy analysis confirmed these findings and revealed, in addition, the presence of PI3P-positive single-membrane vesicles. We hypothesize that these vesicles might be involved in transport processes, likely of proteins and lipids, toward the essential and peculiar parasite compartment, which is the apicoplast. The fact that PI3P metabolism and function in Plasmodium appear to be substantially different from those in its human host could offer new possibilities for antimalarial chemotherapy.
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D’Andrea, Marco Maria, Alberto Antonelli, Andrea Brenciani, Vincenzo Di Pilato, Gianluca Morroni, Simona Pollini, Simona Fioriti, Eleonora Giovanetti und Gian Maria Rossolini. „Characterization of Tn6349, a novel mosaic transposon carrying poxtA, cfr and other resistance determinants, inserted in the chromosome of an ST5-MRSA-II strain of clinical origin“. Journal of Antimicrobial Chemotherapy 74, Nr. 10 (17.07.2019): 2870–75. http://dx.doi.org/10.1093/jac/dkz278.
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AbstractObjectivesTo characterize the genetic element carrying the poxtA oxazolidinone resistance gene found in the poxtA index strain Staphylococcus aureus AOUC-0915 isolated from a cystic fibrosis patient.MethodsThe genetic context of poxtA was investigated by bioinformatics analysis of WGS data of strain AOUC-0915, followed by PCR and confirmatory Sanger sequencing for repetitive regions. Conjugation and electrotransformation experiments were carried out to assess horizontal transferability using S. aureus and Enterococcus faecalis recipients. Production of phage particles was evaluated by PCR using DNA preparations obtained after phage induction. Excision of the transposon carrying poxtA was evaluated by inverse PCR experiments for detection of circular intermediates.ResultspoxtA was found to be associated with a 48 kb composite transposon of original structure, named Tn6349, inserted into a φN315-like prophage. The transposon was bounded by two IS1216 insertion sequences, carried several resistance genes [erm(B), cfr, poxtA and fexB] and exhibited a mosaic structure made by a derivative of plasmid pE35048-oc (previously described in an Enterococcus faecium clinical isolate) and Tn6657, a novel composite transposon carrying the poxtA and fexB genes. Excision ability of Tn6349 as a circular intermediate was demonstrated. Transferability of Tn6349 or modules thereof to S. aureus or E. faecalis by either conjugation or electrotransformation was not detected. Induction of the φN315-like prophage carrying Tn6349 was not observed.ConclusionsThis study describes the structure of Tn6349, a novel composite transposon carrying several resistance determinants to anti-ribosomal drugs, including cfr and poxtA, from an oxazolidinone-resistant MRSA strain. Analysis of Tn6349 revealed a modular structure that could favour the mobilization of its resistance determinants.
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Cohen, J. B., B. Hoffman-Liebermann und L. Kedes. „Structure and unusual characteristics of a new family of transposable elements in the sea urchin Strongylocentrotus purpuratus.“ Molecular and Cellular Biology 5, Nr. 10 (Oktober 1985): 2804–13. http://dx.doi.org/10.1128/mcb.5.10.2804.
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The transposable element family TU of the sea urchin Strongylocentrotus purpuratus, a higher eucaryote, has recently been described (D. Liebermann, B. Hoffman-Liebermann, J. Weinthal, G. Childs, R. Maxson, A. Mauron, S.N. Cohen, and L. Kedes, Nature [London] 306:342-347, 1983). A member of this family, TU4, has an insertion, called ISTU4, of non-TU DNA. ISTU4 is a member of a family of repetitive sequences, which are present in some 1,000 copies per haploid S. purpuratus genome (B. Hoffman-Liebermann, D. Liebermann, L.H. Kedes, and S.N. Cohen, Mol. Cell. Biol. 5:991-1001, 1985). We analyzed this insertion to determine whether it is itself a transposable element. The nucleotide sequence of ISTU4 was determined and showed an unusual structure. There are four, approximately 150 nucleotides long, imperfect direct repeats followed by a single truncated version of these repeats. This region is bounded at either side by approximately 100-nucleotide-long sequences that are not related to each other or to the repeats. Nucleotide sequences at the boundaries of ISTU4-homologous and flanking regions in five genomic clones show that ISTU4 represents a family of sequences with discrete ends, which we call Tsp elements. We showed that the genomic locus that carries a Tsp element in one individual was empty in other individuals and conclude that Tsp elements are a new and different type of transposable element. Tsp elements lack two features common to most other transposable elements: Tsp integration does not result in the duplication of host DNA, and there are no inverted repeats at their termini, although short inverted repeats are present at a distance from the termini.
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Cohen, J. B., B. Hoffman-Liebermann und L. Kedes. „Structure and unusual characteristics of a new family of transposable elements in the sea urchin Strongylocentrotus purpuratus“. Molecular and Cellular Biology 5, Nr. 10 (Oktober 1985): 2804–13. http://dx.doi.org/10.1128/mcb.5.10.2804-2813.1985.
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The transposable element family TU of the sea urchin Strongylocentrotus purpuratus, a higher eucaryote, has recently been described (D. Liebermann, B. Hoffman-Liebermann, J. Weinthal, G. Childs, R. Maxson, A. Mauron, S.N. Cohen, and L. Kedes, Nature [London] 306:342-347, 1983). A member of this family, TU4, has an insertion, called ISTU4, of non-TU DNA. ISTU4 is a member of a family of repetitive sequences, which are present in some 1,000 copies per haploid S. purpuratus genome (B. Hoffman-Liebermann, D. Liebermann, L.H. Kedes, and S.N. Cohen, Mol. Cell. Biol. 5:991-1001, 1985). We analyzed this insertion to determine whether it is itself a transposable element. The nucleotide sequence of ISTU4 was determined and showed an unusual structure. There are four, approximately 150 nucleotides long, imperfect direct repeats followed by a single truncated version of these repeats. This region is bounded at either side by approximately 100-nucleotide-long sequences that are not related to each other or to the repeats. Nucleotide sequences at the boundaries of ISTU4-homologous and flanking regions in five genomic clones show that ISTU4 represents a family of sequences with discrete ends, which we call Tsp elements. We showed that the genomic locus that carries a Tsp element in one individual was empty in other individuals and conclude that Tsp elements are a new and different type of transposable element. Tsp elements lack two features common to most other transposable elements: Tsp integration does not result in the duplication of host DNA, and there are no inverted repeats at their termini, although short inverted repeats are present at a distance from the termini.
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Fielding, Christopher R., W. John Nelson und Scott D. Elrick. „Sequence stratigraphy of the late Desmoinesian to early Missourian (Pennsylvanian) succession of southern Illinois: Insights into controls on stratal architecture in an icehouse period of Earth history“. Journal of Sedimentary Research 90, Nr. 2 (26.02.2020): 200–227. http://dx.doi.org/10.2110/jsr.2020.10.
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ABSTRACT Uncertainty persists over whether repetitive stratal rhythms in the Pennsylvanian of Euramerica (so-called “cyclothems”) were externally forced, in all likelihood by waxing and waning of glacial ice centers on Gondwana, or were controlled by autogenic processes. A key to resolving this dispute is the lateral extent of the individual cyclothems, with broad regional extent (beyond the plausible breadth and length of individual depositional systems such as deltas) arguing in favor of an external forcing control. This study provides a sedimentological and sequence stratigraphic analysis of the middle Pennsylvanian (Desmoinesian to early Missourian in North American stratigraphic terminology, Moscovian to early Kasimovian in the terms of the global stratigraphic nomenclature) succession of the southern Illinois Basin in Illinois, Indiana, and Kentucky, eastern USA. An array of eleven lithofacies is recognized, recording deposition of clastic, humic organic, and bioclastic carbonate sediments on a broad, low-gradient, low-paleolatitude shelf and coastal plain that were undersupplied by sediment. These facies are arranged into thirteen repetitive vertical cycles (sequences), each of which can be traced across the entire basin west to east (perpendicular to the paleoslope direction) across a distance of 250 km. Sequences are bounded by erosion surfaces that define 1–4 km-wide, deeply incised valley-fills (IVFs) that are mostly elongate towards the south-southwest, the dominant direction of paleoflow. In the west–east direction, valley erosion surfaces pass laterally into well-developed paleosols, incised locally by smaller channels. Each of these surfaces is laterally persistent across the basin. IVFs comprise multi-story bodies of conglomerate–breccia and sandstone, passing upward into heterolithic sandstone–mudrock associations, recording fluvial and later estuarine environments. Coal bodies typically occur at the tops of IVFs and are interbedded with heterolithic facies recording tidal influence, indicative of initial flooding by the sea. They are in turn overlain by estuarine and marine mudrocks and bioclastic carbonates, recording the maximum extent of marine flooding in a cycle. Each sequence is completed by heterolithic to sandstone-dominated facies of deltaic aspect that are typically truncated by the next erosion surface (sequence boundary). Plausible modern analogs suggest that sea-level excursions were of the order of 20–40 m. The great lateral persistence of not only the thirteen sequences, but also many of their component beds, argues strongly for an external control on sediment accumulation. Eccentricity-paced glacial cycles in Gondwana are invoked as the most likely cause of the cyclicity. The low-accommodation context of the Illinois Basin (average accumulation rate 6 cm/ky) contributed to the incomplete, condensed, and strongly top-truncated nature of preserved sequences.
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Watt, G. C., S. Boronkay, A. M. Smith und M. A. C. Hotchkis. „The ANSTO Isotope Cycling System“. Radiocarbon 55, Nr. 2 (2013): 308–18. http://dx.doi.org/10.1017/s0033822200057416.
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A number of electronic systems are used on the ANTARES accelerator at ANSTO to implement its fast cycling accelerator mass spectrometry (AMS) capability. The fast cycling system was originally installed and commissioned in 1993 and has recently been updated. This paper describes the more significant of the electronic systems, such as the controller (“sequencer”), the high-voltage power supply (“bouncer”), the fast electrostatic beam chopper, and those used for measurement of the pulsed ion beam current. The sequencer, a programmable 15-bit digital pulse generator, generates the timing and sequencing of the control signals for bouncing voltage selection, beam chopping, Faraday cup current measurement, and rare isotope event measurement. The new sequencer is implemented using a National Instruments FPGA (field programmable gate array) card, programmed using LabVIEW 2010. This device has the benefits of host CPU-independent operation, simple interfacing (PCI), a small footprint, off-the-shelf availability at modest cost, and ease of functionality upgrade. The sequencer provides 15 synchronous digital signals, whose “on” and “off” transitions can be independently specified, in both number and time, with a time resolution of between 0.5 and 128 μs, and with the total duration between repetitions adjustable between 65.5 ms and 8.4 s per cycle. It is hosted by a generic PC because of the low-cost and ubiquity of these. The stand-alone FPGA-based approach ensures that the sequencer determinism is unaffected by processes executing in the host CPU.
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Kager, H., W. J. Wadman und G. G. Somjen. „Conditions for the Triggering of Spreading Depression Studied With Computer Simulations“. Journal of Neurophysiology 88, Nr. 5 (01.11.2002): 2700–2712. http://dx.doi.org/10.1152/jn.00237.2002.
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In spite of five decades of study, the biophysics of spreading depression (SD) is incompletely understood. Earlier we have modeled seizures and SD, and we have shown that currents through ion channels normally present in neuron membranes can generate SD-like depolarization. In the present study, we define the conditions for triggering SD and the parameters that influence its course in a model of a hippocampal pyramidal cell with more complete representation of ions and channels than the previous version. “Leak” conductances for Na+, K+, and Cl− and an ion pump were present in the membrane of the entire cell; fast inactivating voltage dependent conductances for sodium and potassium in the soma; “persistent” conductances in soma and apical dendrite, and K+- and voltage-dependent N-methyl-d-aspartate (NMDA)-controlled conductance in the apical dendrite. The neuron was surrounded by restricted interstitial space and by a “glia-endothelium” system of extracellular ion regulation bounded by a membrane having leak conductances and an ion pump. Ion fluxes and concentration changes were continuously computed as well as osmotic cell volume changes. As long as reuptake into the neuron and “buffering” by glia kept pace with K+ released from the neuron, stimulating current applied to the soma evoked repetitive firing that stopped when stimulation ceased. When glial uptake was reduced, K+ released from neurons could accumulate in the interstitium and keep the neuron depolarized so that strong depolarizing pulses injected into the soma were followed either by afterdischarge or SD. SD-like depolarization was ignited when depolarization spreading into the apical dendrite, activated persistent Na+ current and NMDA-controlled current. With membrane parameters constant, varying the injected stimulating current influenced SD onset but neither the depolarization nor the increase in extracellular K+. Glial “leak” conductance influenced SD duration and SD ignition point. Varying maximal conductances (representing channel density) also influenced SD onset time but not the amplitude of the depolarization. Hypoxia was simulated by turning off the Na-K exchange pump, and this resulted in SD-like depolarization. The results confirm that, once ignited, SD runs an all-or-none trajectory, the level of depolarization is governed by feedback involving ion shifts and glutamate acting on ion channels and not by the number of channels open, and SD is ignited if the net persistent membrane current in the apical dendrites turns inward.
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Syaifullah, M. Djazim. „ANALISIS SUHU MUKA LAUT SELATAN JAWA DAN PENGARUHNYA TERHADAP CURAH HUJAN DAS CITARUM“. Jurnal Sains & Teknologi Modifikasi Cuaca 11, Nr. 2 (16.12.2010): 11. http://dx.doi.org/10.29122/jstmc.v11i2.2181.
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Analisis suhu muka laut (Sea Surface Temperature ~ SST) wilayah selatan Jawadan pengaruhnya terhadap curah hujan di Daerah Aliran Sungai (DAS) Citarum telahdilakukan. Suhu muka laut daerah selatan Jawa dibatasi mulai lintang 90LS sampaidengan 120LS, bujur 1050BT sampai dengan 1140BT, daerah ini yang berbatasanpaling dekat dengan pulau Jawa. Data curah hujan DAS Citarum yang dipakai adalahdata bulanan selama 19 tahun. Analisis historis untuk melihat curah hujan historisDAS Citarum sedangkan analisis time series digunakan untuk melihat pola tahunan(annual), pola musiman (seasonal) maupun pola yang lainnya. Selain itu juga dilakukananalisis spektral untuk melihat secara jelas pola curah hujannya. Terhadap data SSTjuga dilakukan analisis yang sama. Setelah itu dilakukan korelasi antara nilai SSTmasing-masing grid dengan curah hujan DAS Citarum. Hasil analisis menunjukkanbahwa curah hujan DAS Citarum mempunyai periode yang dominan yaitu tahunan(annual) dan yang kedua adalah sekitar tiga tahunan. Analisis terhadap suhu muka lautmenunjukkan rerata suhu maksimum SST mencapai 29.30C terjadi pada awal bulanMaret dan suhu minimum mencapai 26.20C terjadi pada pertengahan bulan September. Hasil analisis spektral menunjukkan bahwa selain perulangan tahunan, suhu muka laut juga mengalami perulangan musiman dan perulangan beberapa tahunan meskipun tidak tampak jelas. Korelasi curah hujan dengan suhu muka laut mempunyai nilai berkisar antara 0.37 sampai dengan 0.64. Nilai korelasi terbesar terdapat pada lintang 08o LS sedangkan terhadap bujur, korelasi terbesar terlihat pada bujur 112o BT.Analysis of Sea Surface Temperature (SST) south of Java and its influence on rainfallin the Citarum watershed has been done Sea surface temperature in the area boundedby 9oS to 12oS latitude and 105oE to 114oE longitude, on the border of this areaclosest to the island of Java. History analysis has done to see the rainfall history ofCitarum river basin, while the analysis of time series used to see annual patterns,seasonal pattern and other patterns. It also performed spectral analysis to see clearlythe pattern of rainfall. Against the sea surface temperature data are also performeda similar analysis. The analysis showed that the rainfall of Citarum watershed has adominant period of the annual and the second is about three years. The analysis ofthe sea surface temperatures show an average maximum temperature reached 29.30Coccurred in early March and the lowest temperature reached 26.20C occurred in mid-September. The spectral analysis of sea surface temperature showed that in additionto the annual repetition appears also seasonal and cycles of some years although notobvious. Correlation of rainfall with sea surface temperature has a value ranging from0.37 to 0.64. Against latitude the biggest correlation value contained in latitude 08oSwhile against longitude the largest correlation seen in 112o E.
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Lužar, Borut, Pascal Ochem und Alexandre Pinlou. „On Repetition Thresholds of Caterpillars and Trees of Bounded Degree“. Electronic Journal of Combinatorics 25, Nr. 1 (16.03.2018). http://dx.doi.org/10.37236/6793.
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The repetition threshold is the smallest real number $\alpha$ such that there exists an infinite word over a $k$-letter alphabet that avoids repetition of exponent strictly greater than $\alpha$. This notion can be generalized to graph classes. In this paper, we completely determine the repetition thresholds for caterpillars and caterpillars of maximum degree $3$. Additionally, we present bounds for the repetition thresholds of trees with bounded maximum degrees.
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Rosenfeld, Matthieu. „Another Approach to Non-Repetitive Colorings of Graphs of Bounded Degree“. Electronic Journal of Combinatorics 27, Nr. 3 (04.09.2020). http://dx.doi.org/10.37236/9667.
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We propose a new proof technique that applies to the same problems as the Lovász Local Lemma or the entropy-compression method. We present this approach in the context of non-repetitive colorings and we use it to improve upper-bounds relating different non-repetitive chromatic numbers to the maximal degree of a graph. It seems that there should be other interesting applications of the presented approach.
In terms of upper-bounds our approach seems to be as strong as entropy-compression, but the proofs are more elementary and shorter. The applications we provide in this paper are upper bounds for graphs of maximal degree at most $\Delta$: a minor improvement on the upper-bound of the non-repetitive chromatic number, a $4.25\Delta +o(\Delta)$ upper-bound on the weak total non-repetitive chromatic number, and a $ \Delta^2+\frac{3}{2^{1/3}}\Delta^{5/3}+ o(\Delta^{5/3})$ upper-bound on the total non-repetitive chromatic number of graphs. This last result implies the same upper-bound for the non-repetitive chromatic index of graphs, which improves the best known bound.
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Sbarbaro, D., M. Tomizuka und B. León de la Barra. „Repetitive Control System Under Actuator Saturation and Windup Prevention“. Journal of Dynamic Systems, Measurement, and Control 131, Nr. 4 (21.05.2009). http://dx.doi.org/10.1115/1.3117207.
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This work provides an analysis of the steady state response of a prototype repetitive controller applied to a class of nonlinear systems, i.e., systems with actuator saturation. First, it is shown that the steady state solution of the closed loop nonlinear system can be obtained by an iterative Picard process, which establishes the periodic nature of the steady state solution. Second, the conditions for obtaining bounded steady state responses are analyzed for a saturating nonlinearity commonly found in mechatronic applications. Valuable insight is provided into the effects of input signals and saturating actuators on the closed loop performance of a prototype repetitive controller. In order to improve the transient closed loop response, a simple antiwindup strategy tailored to repetitive controllers is proposed.
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Sakthivel, R., K. Raajananthini, P. Selvaraj und Y. Ren. „Design and Analysis for Uncertain Repetitive Control Systems With Unknown Disturbances“. Journal of Dynamic Systems, Measurement, and Control 140, Nr. 12 (23.07.2018). http://dx.doi.org/10.1115/1.4040663.
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In this paper, the periodic tracking problem is considered for a class of continuous system with uncertainty, time-varying delay, and unknown bounded external disturbances. To be precise, in order to attenuate the unknown disturbance effectively, the equivalent-input-disturbance (EID) approach is incorporated into the developed algorithm. Then, the sufficient conditions that guarantee the asymptotic tracking performance of the system understudy are established based on the Lyapunov stability theorem. More precisely, Schur complement and free-weighting matrix approach are utilized to derive the main results. Moreover, the proposed EID-based modified repetitive controller (MRC) not only rejects the unknown external disturbance but also deals with the dead zone effect. Finally, two simulation examples are presented to verify the superiority of the proposed EID-based repetitive controller over the conventional repetitive controller.
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Chen, Qiang, Xinqi Yu, Mingxuan Sun, Chun Wu und Zijun Fu. „Adaptive Repetitive Learning Control of PMSM Servo Systems with Bounded Nonparametric Uncertainties: Theory and Experiments“. IEEE Transactions on Industrial Electronics, 2020, 1. http://dx.doi.org/10.1109/tie.2020.3016257.
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Chen, Cheng-Lun, und George T. C. Chiu. „Spatially Periodic Disturbance Rejection With Spatially Sampled Robust Repetitive Control“. Journal of Dynamic Systems, Measurement, and Control 130, Nr. 2 (29.02.2008). http://dx.doi.org/10.1115/1.2837306.
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Repetitive controllers have been shown to be effective for tracking periodic reference commands or for rejecting periodic disturbances. Typical repetitive controllers are synthesized in temporal domain where the periods of the reference or disturbance signals are assumed to be known and stationary. For periodic references and disturbances with varying periods, researchers usually resort to adaptive and robust control approaches. For rotational motion systems where the disturbances or reference signals are spatially periodic (i.e., periodic with respect to angular displacement), the temporal period of the disturbance and reference signals will be inversely proportional to the rotational speed and vary accordingly. Motivating by reducing halftone banding for laser printers, we propose a design framework for synthesizing spatially sampled repetitive controller by reformulating a linear time-invariant system subject to spatially periodic disturbances using angular displacement as the independent variable. The resulting nonlinear system can be represented as a quasi-linear parameter-varying (quasi-LPV) system with the angular velocity as one of the varying state-dependent parameters. An LPV self-gain–scheduling controller that includes a spatially sampled repetitive control can be designed to take into consideration bounded model uncertainty and input nonlinearity, such as actuator saturation. Using the signal from an optical encoder pulse as a triggering interrupt, experimental results verified the effectiveness of the proposed approach in rejecting spatially periodic disturbances that cannot be compensated with fixed period temporal repetitive controllers.
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Kelly, Michael, und Lorenzo Sadun. „Pattern Equivariant Mass Transport in Aperiodic Tilings and Cohomology“. International Mathematics Research Notices, 11.03.2020. http://dx.doi.org/10.1093/imrn/rnz310.
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Abstract Suppose that we have a repetitive and aperiodic tiling ${\textbf{T}}$ of ${\mathbb{R}}^n$ and two mass distributions $f_1$ and $f_2$ on ${\mathbb{R}}^n$, each pattern equivariant (PE) with respect to ${\textbf{T}}$. Under what circumstances is it possible to do a bounded transport from $f_1$ to $f_2$? When is it possible to do this transport in a strongly or weakly PE way? We reduce these questions to properties of the Čech cohomology of the hull of ${\textbf{T}}$, properties that in most common examples are already well understood.
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Saorín, Manuel, und Alexandra Zvonareva. „Lifting of recollements and gluing of partial silting sets“. Proceedings of the Royal Society of Edinburgh: Section A Mathematics, 07.06.2021, 1–49. http://dx.doi.org/10.1017/prm.2021.3.
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This paper focuses on recollements and silting theory in triangulated categories. It consists of two main parts. In the first part a criterion for a recollement of triangulated subcategories to lift to a torsion torsion-free triple (TTF triple) of ambient triangulated categories with coproducts is proved. As a consequence, lifting of TTF triples is possible for recollements of stable categories of repetitive algebras or self-injective finite length algebras and recollements of bounded derived categories of separated Noetherian schemes. When, in addition, the outer subcategories in the recollement are derived categories of small linear categories the conditions from the criterion are sufficient to lift the recollement to a recollement of ambient triangulated categories up to equivalence. In the second part we use these results to study the problem of constructing silting sets in the central category of a recollement generating the t-structure glued from the silting t-structures in the outer categories. In the case of a recollement of bounded derived categories of Artin algebras we provide an explicit construction for gluing classical silting objects.
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Alam, Sultana Lubna. „Many hands make light work: towards a framework of digital co-production to co-creation on social platforms“. Information Technology & People ahead-of-print, ahead-of-print (23.09.2020). http://dx.doi.org/10.1108/itp-05-2019-0231.
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PurposeRecent technological advances have enabled consumers and citizens to contribute to organizational processes through co-production and co-creation in ways that challenge traditional co-production. However, the practices and capabilities for value co-creation are less understood, particularly in an increasingly networked social government ecosystem. The purpose of this research is to examine the enablement of new digital co-production practices in social media platforms (SMPs) and theorize SMP-enabled digital co-production vis-à-vis traditional co-production for public sector.Design/methodology/approachPrimarily using principles of interpretivist approaches, a qualitative content analysis of communication practices (i.e. genres) observed within Australian government Facebook pages was carried out to examine the salient digital forms of co-production practices.FindingsSMPs enable new practices in digital co-production for public sector (information dissemination, Q&A, feedback and co-creation), ranging from lower to higher intensity in terms of resource integration, scale of contributions, engagement and extent of relationship vis-à-vis traditional co-production.Research limitations/implicationsThis research is bounded by its geographical emphasis on Australian Federal government. Hence, the results may not be readily transferable to other contexts.Practical implicationsOur framework offers an array of choices for digital co-production strategies to suit agency's focus and goals for engagement in the Facebook Pages. As agencies progress to reach higher intensity co-production, public engagement and impact increases.Originality/valueThe paper contributes to co-production in social government ecosystem by increasing the theoretical and practical understanding of new form of SMP-enabled digital co-production defined as “small-scale, repetitive, user-driven co-production that is flexible, durable, ad-hoc, and sporadic, where many hands make light work”. The proposed “co-production to co-creation” framework provides valuable guideline for enhancing public service provision via SMPs.
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Klug, Florian. „Modelling oscillations in the supply chain: the case of a just-in-sequence supply process from the automotive industry“. Journal of Business Economics, 05.06.2021. http://dx.doi.org/10.1007/s11573-021-01049-6.
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AbstractPervasive and ubiquitous oscillations, mapping the repetitive variation in time of a specific state, are well known as abundant phenomena in research and practice. Motivated by the success of oscillators in the modelling, analysis and control of dynamical systems, we developed a related approach for the dynamic description of supply chains. This paper aims to introduce a generic oscillator model for supply chains by the original application of oscillator equations. Therefore an established oscillator model for deductive modelling of supply chain echelons is used. With the help of coupled van der Pol oscillators, the dynamical interaction of an inventory system is described and applied to a real-life supply process in automotive industry. According to its reductionist approach only two differential equations are used to analyse a Just-in-Sequence supply process in car industry. Based on the fact that any oscillatory state can be reduced to the phase of the oscillation (phase reduction), a phase space map is generated. This compact visual reference of the supply process can act as the quantitative basis for an adaptive control mechanism during its operation. By delaying or accelerating the inventory oscillations of the supplier stock a detuned coupled supply process can be re-synchronised without changing the amplitude. An additional analysis of Hilbert transform is applied to determine the boundaries of phase-locking between the inventory oscillation phases, where the instantaneous phases are bounded. Furthermore parameters of the synchronisation threshold and the transient phases between synchronous and non-synchronous regimes have been investigated, supported by an Arnold tongue representation. The investigations show that with the help of a generic oscillatory model it is possible to measure and quantify phenomena of inventory dynamics in supply chains. Especially the analysis of synchronisation phenomena with the help of phase space and Arnold tongue representations foster developments of performance measurement in supply chain management.