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Proposes and implements a method for active compensation for vibrations, without contact, to eliminate the vibrations of a moving paper band in a printing press. Description of the printing test bench; Theoretical vibration frequencies of the natural modes of a paper band; Identification results for the first natural mode of vibration.

The crossing number of a graph is a significant measure that indicates the complexity of the graph and the difficulty of visualizing it. In this paper, we examine the crossing numbers of join products involving the complete graph K 5 with discrete graphs, paths, and cycles. We analyze optimal drawings of K 5 , identify all five non-isomorphic drawings, and address previously hypothesized crossing numbers for K 5 + P n , and K 5 + C n . Through a simplified approach, we first establish cr (K 5 + D n) and then extend our method to prove the crossing numbers cr (K 5 + P n) and cr (K 5 + C n) . These results also lead to new hypotheses for cr (W m + S n) and cr (W m + W n) involving wheels and stars. Our findings correct previous inaccuracies in the literature and provide a foundation for future research. [ABSTRACT FROM AUTHOR]

In growth-cycle models, consumption smoothing motivates procyclical household savings and monopolistic competition engenders countercyclical horizontal R&D at fixed costs of capital. However, data in the US and in 15 OECD countries indicate countercyclical household saving, procyclical R&D, and high volatility. This paper explains the observed cyclical properties by realistic income taxes, R&D subsidies, R&D labor, and depreciation. R&D subsidies promote R&D to increase productivity by trading the levels for the varieties of intermediates. R&D-subsidy payments increase consumption and decrease household saving rates by raising taxable income beyond output, thus hindering future R&D and growth. Anticipated R&D-subsidy payments increase household-saving rates by raising returns to saving, thus promoting future R&D and growth. The US taxes yield unstable fluctuations with consecutive periods of R&D, low saving rates, and strong growth as in the technology boom. R&D labor and partial depreciation strengthen the roles of saving and R&D in attaining high volatility. [ABSTRACT FROM AUTHOR]

A vertex-edge perfect Roman dominating function on a graph G = (V; E) (denoted by ve-PRDF) is a function f: V (G) f0; 1; 2g such that for every edge uv 2 E, maxf f (u); f (v)g, 0, or u is adjacent to exactly one neighbor w such that f (w) = 2, or v is adjacent to exactly one neighbor w such that f (w) = 2. The weight of a ve-PRDF on G is the sum w(f) = P v2V f (v). The vertex-edge perfect Roman domination number of G (denoted by p veR(G)) is the minimum weight of a ve-PRDF on G. In this paper, we first show that vertex-edge perfect Roman dominating is NP-complete for bipartite graphs. Also, for a tree T, we give upper and lower bounds for p veR(T) in terms of the order n, l leaves and s support vertices. Lastly, we determine p veR(G) for Petersen, cycle and Flower snark graphs. [ABSTRACT FROM AUTHOR]

Considerable studies have examined the relationship between commodity markets and stock markets. This paper studies the cyclical relationship between commodity markets and stock markets with implications for investing based on index relationships. Stock markets are represented by the U.S. S&P 500 index and aggregate commodity markets by the U.S. producer price index (PPI). Tradeable market indexes readily available to investors, namely the S&P GSCI Index and the Bloomberg Commodity Index (BCOM), are also studied. An optimal bandpass filter is used to estimate the cyclical component using a pricing-performance measure of the S&P 500 relative to the PPI, based on annual data from 1871 to 2022. The S&P GSCI and the BCOM indexes are also used to test the robustness of the findings. The impacts of the financial crisis of 2008 and the coronavirus pandemic are also assessed. The overriding conclusion of the study is that a cyclical relationship exists between stock markets and commodity markets for both aggregate and tradeable indexes which can last, from peak to peak, approximately 31 years. Measuring returns and risks in a manner consistent with these cycles can shed new light on the usefulness of commodity investing via tradeable indexes in seeking efficient portfolios. [ABSTRACT FROM AUTHOR]

Let K = K(a, p; λ1, λ2) be the multigraph with: the number of parts equal to p; the number of vertices in each part equal to a; the number of edges joining any two vertices of the same part equal to λ1; and the number of edges joining any two vertices of different parts equal to λ2. The existence of C4-factorizations of K has been settled when a is even; when a ≡ 1 (mod 4) with one exception; and for very few cases when a ≡ 3 (mod 4). The existence of Cz-factorizations of K has been settled when a ≡ 1 (mod z) and λ1 is even, and when a ≡ 0 (mod z). In this paper, we give a construction for Cz-factorizations of K for z = 2a when a is even. [ABSTRACT FROM AUTHOR]

In this paper, time-invariant spatially coupled low-density parity-check convolutional codes (SC-LDPC-CCs) are considered, and the connections existing between their low-weight codewords and cycles in their Tanner graphs are studied. Using the polynomial representation of these codes, we show that parity-check matrices having columns with weight ≥2 can be analyzed considering a certain number of parity-check sub-matrices having regular columns with weight 2. These sub-matrices are associated to cycles in the code Tanner graph and define as many codes we denote as component codes. Based on this observation, we find that codewords of the main code can be expressed as combinations of codewords of the component codes. The design of codes free of codewords up to a certain weight is also addressed. We show that low-weight codewords in the main code can be avoided by removing some types of cycles in its Tanner graph. Our design approach is applied to some well-known ensembles of SC-LDPC-CCs to prove its effectiveness. [ABSTRACT FROM AUTHOR]

Circuits in a graph are interesting structures and identifying them is of an important relevance for many applications. However, enumerating circuits is known to be a difficult problem, since their number can grow exponentially. In this paper, we propose fast parallel approaches for enumerating elementary circuits of directed graphs based on graphics processing unit (GPU). Our algorithms are based on a massive exploration of the graph in a breadth-first search strategy. Algorithm V-FEC explores the graph starting from different vertices simultaneously. To further reduce the search space, we present T-FEC, another algorithm that uses triplets as an initial set to start exploring. To the best of our knowledge, those are the first parallel GPU-based algorithms for finding all circuits of a given graph. In addition, they find circuits of a given length and circuits with a specific vertex or edge. The evaluation results show that the proposed approaches achieve up to 190x speed-up over Johnson's algorithm, one of the most efficient sequential algorithms for finding circuits. [ABSTRACT FROM AUTHOR]

Let R be a ring with unity. In this paper, we introduce a new graph associated with R called the simple-intersection graph of R, denoted by GS (R). The vertices of GS (R) are the nonzero ideals of R, and two vertices are adjacent if and only if their intersection is a nonzero simple ideal. We study the interplay between the algebraic properties of R, and the graph properties of GS (R) such as connectedness, bipartiteness, girth, dominating sets, etc. Moreover, we determine the precise values of the girth and diameter of GS (R), as well as give a formula to compute the clique and domination numbers of GS (R). [ABSTRACT FROM AUTHOR]

Designs and constructions of quasi-cyclic (QC) LDPC codes for the AWGN channel are presented. The codes are constructed based on the conventional parity-check matrices of Reed–Solomon (RS) codes and are referred to as RS-QC-LDPC codes. Several classes of RS-QC-LDPC codes are given. Cycle structural properties of the Tanner graphs of codes in these classes are analyzed and specific methods for constructing codes with girth at least eight and reducing their short cycles are presented. The designed codes perform well in both waterfall and low error-rate regions. [ABSTRACT FROM AUTHOR]

This is the second in a series of papers on conformal tilings. The overriding themes here are local isomorphisms, hierarchical structures, and the conformal "type" problem. Conformal tilings were introduced by the authors in 1997 with a conformally regular pentagonal tiling of the plane. This and even more intricate hierarchical patterns arise when tilings are repeatedly subdivided. Deploying a notion of expansion complexes, we build two-way infinite combinatorial hierarchies and then study the associated conformal tilings. For certain subdivision rules the combinatorial hierarchical properties are faithfully mirrored in their concrete conformal realizations. Examples illustrate the theory throughout the paper. In particular, we study parabolic conformal hierarchies that display periodicities realized by Mobius transformations, motivating higher level hierarchies that will emerge in the next paper of this series. [ABSTRACT FROM AUTHOR]

This paper introduces a novel solution for building fault aware memory built-in self-test infrastructure based on rules of fault periodicity and regularity in memories and test algorithms. These periodicity and regularity rules are described via special internal structures named fault periodicity table (FPT) and test algorithm template (TAT). Three dimensions of evolution are considered as inputs for forming the mentioned structures: memory cells, multidimensional memory circuits, and memory systems for systems-on-chip where memories are distributed in different subchips. Each column of FPT corresponds to a fault nature which can be associated with a variety of different test mechanisms while each row of FPT corresponds to a fault family determined by the complexity of fault sensitization. FPT allows considering any large number of faults in one table while TAT allows constructing test algorithms without using test algorithm generation tools. Experimental results of the solution applied to both Planar-based (90/65/45/28 nm) and FinFET-based (16/10/7 nm) memory technologies are adduced also in this paper. [ABSTRACT FROM AUTHOR]

Let G be a connected graph and g be a non-negative integer. A vertex set S of graph G is called a g-extra cut if G − S is disconnected and each component of G − S has at least g + 1 vertices. The g-extra connectivity of G is the minimum cardinality of a g-extra cut of G if G has at least one g-extra cut. For two graphs G 1 = (V 1 , E 1) and G 2 = (V 2 , E 2) , the strong product G 1 ⊠ G 2 is defined as follows: its vertex set is V 1 × V 2 and its edge set is { (x 1 , x 2) (y 1 , y 2) | x 1 = x 2 and y 1 y 2 ∈ E 2 ; or y 1 = y 2 and x 1 x 2 ∈ E 1 ; or x 1 x 2 ∈ E 1 and y 1 y 2 ∈ E 2 } , where (x 1 , x 2) , (y 1 , y 2) ∈ V 1 × V 2 . In this paper, we obtain the g-extra connectivity of the strong product of two paths, the strong product of a path and a cycle, and the strong product of two cycles. [ABSTRACT FROM AUTHOR]

This paper is an application of delay differential equations to entrepreneurship and unemployment. It shows that the results of empirical studies can be replicated through a simple DDE. The paper also carries out a comparative study between a solution of a DDE and the observation of cyclic behaviors. The calculated delay (and growth rate) of the entrepreneurship DDE for the US and Spain is 1.25 years (1.25), for Ireland is 1.75 years (0.89), and for the UK is 2 years (0.78). The delay (and growth rate) of the unemployment DDE for the US and Ireland is 1.5 years (1.04), for Spain is 2 years (0.78), and for the UK is 2.5 years (0.62). [ABSTRACT FROM AUTHOR]

In this paper we consider the Glauber dynamics for the one-dimensional Ising model with dissipation, in a mesoscopic regime obtained by letting inverse temperature and volume go to infinity with a suitable scaling. In this limit the magnetization has a periodic behavior. Self-organized collective periodicity has been shown for many mean-field models but, to our knowledge, this is the first example with short-range interaction. This supports the view that self-organized periodicity is not linked with the mean-field assumption but it is a thermodynamic phenomenon compatible with short range interactions. [ABSTRACT FROM AUTHOR]

This paper proposes two heuristic algorithms for finding fixed-length circuits and cycles in undirected edge-weighted graphs. It focusses particularly on a largely unresearched practical application where we are seeking attractive round trips for pedestrians and joggers in urban street networks. Our first method is based on identifying suitable pairs of paths that are combined to form a solution; our second is based on local search techniques. Both algorithms display high levels of accuracy, producing solutions within just a few meters of the target. Run times for the local search algorithm are also short, with solutions in large cities often being found in less than one second. [ABSTRACT FROM AUTHOR]

Purpose -- The purpose of this paper is to investigate two famous postulates of the Schumpeterian doctrine and its implications for the US economy. Design/methodology/approach -- Analytically, the authors investigate whether sector size matters for sectoral: technological change and stability, as expressed through the relevant quantitative measures and variables. To this end, the authors test a number of relevant models that express the various forms of this relationship. More precisely, the authors use panel data for the 14 main sectors of economic activity in the USA over the period 1957-2006, just before the first signs of the US and global recession made their appearance. Findings -- The results seem to be in line with the Schumpeterian postulate that market size matters for technological change and economic stability, for the US economy (1957-2006). Clearly, further research would be of great interest. Originality/value -- This work contributes to the literature in the following ways: first, it provides an extensive review of the literature on the subject and adopts two relevant methodological approaches. Second, based on these quantitative approaches, the paper offers a complete investigation of two famous postulates of the Schumpeterian theory for the US economy, and it is the first, to the best of the authors' knowledge, to do so by sector of economic activity, in a panel data framework. Third, the paper uses a wide data set (1957-2006) to examine the US economy up until the first signs of the US and global economic recession made their appearance. [ABSTRACT FROM AUTHOR]

In this paper, we have studied a practical design of a broadband linear-to-circular polarizer based on a self-complementary metasurface composed of zigzag-shaped metal strips printed on a dielectric substrate. The term self-complementary indicates that the structure is identical to its complement, except for some translation smaller than the periodicity. This property together with the nonresonant response of the unit cells ensures broadband conversion from linear polarization to circular polarization. Although we have experimentally achieved a relative 3-dB-axial-ratio (AR) bandwidth (BW) of 53%, in principle, it could reach up to 70.5%. Moreover, the studied metasurface has a very small periodicity, which avoids any higher order grating lobes and provides angular stability of the phenomenon. In fact, the relative 3-dB-AR BW obtained in experiments stays always above 40% for incidence angles within ±30°. An excellent agreement was achieved among theory, simulations, and experiments. [ABSTRACT FROM PUBLISHER]

This paper proposes a new modeling framework capturing both the long‐run and the cyclical components of a time series. As an illustration, we apply it to four US macro series, namely, annual and quarterly real gross domestic product (GDP) and GDP per capita. The results indicate that the behavior of US GDP can be captured accurately by a model incorporating both stochastic trends and stochastic cycles that allows for some degree of persistence in the data. Both appear to be mean reverting, although the stochastic trend is nonstationary, while the cyclical component is stationary, with cycles repeating themselves every 6–10 years. [ABSTRACT FROM AUTHOR]

The characteristic curve (CC) of a production system is a function describing the behavior of cycle time (CT) versus throughput (TP). In systems with unlimited buffers, this function typically has a knee-type shape. Operating the system below the knee is not efficient, since TP can be increased without an appreciable increase in CT. Operating above the knee is also counterproductive—CT becomes extremely large without a significant increase of TP. Thus, the desirable operating point is at the knee. In order to operate the system at or close to the knee, some knowledge of its CC is necessary. In this paper, an analytical/empirical method for calculating CCs of single-product re-entrant lines is developed using the so-called bottleneck workcenter model of systems at hand. Based on this method, open- and closed-loop raw material release policies, which ensure operating at the desired point of CC, are provided. The development is carried out in terms of the First Buffer First Served (FBFS) and Last Buffer First Served (LBFS) dispatch policies, although CCs for other dispatch policies can be investigated in a similar manner. In addition, it is shown by simulations that the method developed can be used for evaluating CC of a model of a scaled-down wafer fab, which includes multiple workcenters and batching, as long as the severity of the bottleneck workcenter is sufficiently high. [ABSTRACT FROM AUTHOR]

Discovering periodic patterns in a customer transaction database is the task of identifying itemsets (sets of items or values) that periodically appear in a sequence of transactions. Numerous methods can identify patterns exhibiting a periodic behavior. Nonetheless, a problem of these traditional approaches is that the concept of periodic behavior is defined very strictly. Indeed, a pattern is considered to be periodic if the amount of time or number of transactions between all pairs of its consecutive occurrences is less than a fixed maxPer (maximum periodicity) threshold. As a result, a pattern can be eliminated by a traditional algorithm for mining periodic patterns even if all of its periods but one respect the maxPer constraint. Consequently, many patterns that are almost always periodic are not presented to the user. But these patterns could be considered as interesting as they generally appear periodically. To address this issue, this paper suggests to use three measures to identify periodic patterns. These measures are named average, maximum and minimum periodicity, respectively. They are each designed to evaluate a different aspect of the periodic behavior of patterns. By using them together in a novel algorithm called Periodic Frequent Pattern Miner, more flexibility is given to users to select patterns meeting specific periodic requirements. The designed algorithm has been evaluated on several datasets. Results show that the proposed solution is scalable, efficient, and can identify a small sets of patterns compared to the Eclat algorithm for mining all frequent patterns in a database. [ABSTRACT FROM AUTHOR]

The adoption of the virtual synchronous generator (VSG) has attracted wide attention because of the equivalent operating mechanism as a synchronous generator, providing a feasible scheme for the distributed generation connected to utility grid. However, the delivered power and frequency of the VSG may easily oscillate when the dramatic power fluctuation occurred in the distribution generation system. Fortunately, the oscillation can be damped though adjusting the rotating inertia and damping coefficient. Thus, to investigate the influences of parameters perturbation on the active power and frequency for a VSG, the small-signal model is derived and the dynamic performances are analyzed in detail. Then, based on the results of parameters analysis, an adaptive control strategy is proposed in this paper. And an optimal damping ratio can be maintained throughout the whole process of operation to suppress the oscillation of power and frequency. Therefore, the dynamic performances of the VSG are enhanced since the dynamic indexes such as the response time and overshoots are optimized. In the end, a prototype of single-phase VSG has been built and the proposed adaptive control strategy has been verified through experimental results. [ABSTRACT FROM AUTHOR]

The paper considers a general neural network model with impulses at a given sequence of instants, discontinuous neuron activations, delays, and time-varying data and inputs. It is shown that when the neuron interconnections satisfy an M-matrix condition, or a dominance condition, then the state solutions and the output solutions display a common asymptotic behavior as time t → +∞. It is also shown, via a new technique based on prolonging the solutions of the delayed neural network to -∞, that it is possible to select a unique special solution that is globally exponentially stable and can be considered as the unique global attractor for the network. Finally, this paper shows that for almost periodic data and inputs the selected solution is almost periodic; moreover, it is robust with respect to a large class of perturbations of the data. Analogous results also hold for periodic data and inputs. A by-product of the analysis is that a sequence of almost periodic impulses is able to induce in the generic case (nonstationary) almost periodic solutions in an otherwise globally convergent nonimpulsive neural network. To the authors' knowledge the results in this paper are the only available results on global exponential stability of the unique periodic or almost periodic solution for a general neural network model combining three main features, i.e., impulses, discontinuous neuron activations and delays. The results in this paper are compared with several results in the literature dealing with periodicity or almost periodicity of some subclasses of the neural network model here considered and some hints for future work are given. [ABSTRACT FROM AUTHOR]

Microwave band gap structures exhibit certain stop band characteristics based on the periodicity, impedance contrast and effective refractive index contrast. These structures though formed in one-, two- and three-dimensional periodicity, are huge in size. In this paper, microstrip-based microwave band gap structures are formed by removing the substrate material in a periodic manner. This paper also demonstrates that these structures can serve as a non-destructive characterization tool for materials, a duplexor and frequency selective coupler. The paper presents both experimental results and theoretical simulation based on a commercially available infinite element methodology for comparison. [ABSTRACT FROM AUTHOR]

Abstract: A simple graph is reflexive if its second largest eigenvalue does not exceed 2. A graph is treelike (sometimes also called a cactus) if all its cycles (circuits) are mutually edge-disjoint. In a lot of cases one can establish whether a given graph is reflexive by identifying and removing a single cut-vertex (Theorem 1). In this paper we prove that, if this theorem cannot be applied to a connected treelike reflexive graph G and if all its cycles do not have a common vertex (do not form a bundle), such a graph has at most five cycles (Theorem 2). On the same conditions, in Theorem 3 we find all maximal treelike reflexive graphs with four and five cycles. [Copyright &y& Elsevier]

Alspach et al. (J. Austral. Math. Soc. 56(3) (1994) 391–402) constructed an infinite family of tetravalent graphs M(a; m, n) and proved that if n ≥ 9 be odd and a 3 ≡ 1 (mod n) , then M(a; 3, n) is half-arc-transitive. In this paper, we show that if a 3 ≡ 1 (mod n) , then M(a; 3, n) is an infinite family of tetravalent half-arc-transitive Cayley graphs for all integers n except 7 and 14. [ABSTRACT FROM AUTHOR]

In this paper, we present some sufficient conditions for the oscillation of all solutions of a second order forced impulsive delay differential equation with damping term. Three factors-impulse, delay and damping that affect the interval qualitative properties of solutions of equations are taken into account together. The results obtained in this paper extend and generalize some of the the known results for forced impulsive differential equations. An example is provided to illustrate the main result. [ABSTRACT FROM AUTHOR]

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Earlier research work on the dynamics of the brain, disclosing the existence of crucial events, is revisited for the purpose of making the action of crucial events, responsible for the 1/ f −noise in the brain, compatible with the wave-like nature of the brain processes. We review the relevant neurophysiological literature to make clear that crucial events are generated by criticality. We also show that although criticality generates a strong deviation from the regular wave-like behavior, under the form of Rapid Transition Processes, the brain dynamics also host crucial events in regions of nearly coherent oscillations, thereby making many crucial events virtually invisible. Furthermore, the anomalous scaling generated by the crucial events can be established with high accuracy by means of direct analysis of raw data, suggested by a theoretical perspective not requiring the crucial events to yield a visible physical effect. The latter follows from the fact that periodicity, waves and crucial events are the consequences of a spontaneous process of self-organization. We obtain three main results: (a) the important role of crucial events is confirmed and established with greater accuracy than previously; (b) we demonstrate the theoretical tools necessary to understand the joint action of crucial events and periodicity; (c) we argue that the results of this paper can be used to shed light on the nature of this important process of self-organization, thereby contributing to the understanding of cognition. [ABSTRACT FROM AUTHOR]

In this paper, we study the existence of an asymptotically periodic solution of a Volterra integral equation on the time scale ..., which we call a quantum Volterra integral equation. In the process, we study the existence of periodic solutions of an associated equation on the time scale ..., which is an extension of q... We employ Schauder's fixed point theorem in the analysis. [ABSTRACT FROM AUTHOR]

This paper derives necessary conditions such that cyclical policies may be optimal in concave, two state variable (economic) control problems. These conditions identify four different routes. One major implication is that two of these four conditions may be met by separable models. This possibility has been overlooked so far. Therefore, even separable and structurally very simple models may be characterized by optimal cyclical policies. Indeed, it will be shown that stable limit cycles exist for concave and separable control problems. [ABSTRACT FROM AUTHOR]

Since the curved surface of a cable-network reflector is generally approximated by regular flat facets, the electromagnetic performance of the cable-network reflector is determined by the size and shape of the facets. In many cases, the geometric approximation errors of the facets are periodically distributed on the surface, which can result in strong grating lobes. First, in this paper, the periodicity of the geometric approximation error and the effects of this periodicity on the EM performance are investigated. Second, the periodic geometric approximation errors of the regularly faceted configurations are disturbed by three proposed approaches, and three new types of surface configurations are thus formed. The first approach is to introduce radial direction disturbance parameters, the second one is to change the shape of the outlines and the last one is to use a Penrose-tiling-like configuration. The first two approaches are carried out in combination with the optimization strategies. Finally, the effects of the mentioned disturbance parameters on the EM performance are simulated, and some numerical examples are given to show that the surface configurations proposed in this paper can reduce the grating lobes level obviously, without either decreasing the gain or increasing the structural complexity of the cable-network reflectors. [ABSTRACT FROM PUBLISHER]

Background: Cancer has become a global health problem. China still suffers continuous increasing cancer mortality. To study the trend of cancer mortality in rural China, this paper established an Age-Period-Cohort model to discuss the age effect, period effect and cohort effect on cancer mortality in rural China. Methods: The data were collected from the “China Health Statistical Yearbook” from 1990 to 2010. Collected data were analyzed by Age-Period-Cohort model and Intrinsic Estimation method. Results: The age effect on the total cancer mortality represented a V trend. Compared with Group 0–4, Group 5–9 showed 71.87% lower cancer mortality risk. Compared with Group 5–9, Group 75–79 showed 38 times higher cancer mortality risk. The period effect on the total cancer mortality risk weakened firstly but then increased. It increased by 35.70% from 1990 to 2010, showing an annual average growth of 1.79%. The cohort effect on the total cancer mortality risk weakened by totally 84.94% from 1906–1910 to 2005–2010. Three “deterioration periods” and three “improvement periods” were witnessed during this period. The malignant cancer mortality varied similarly with the total cancer mortality, while benign cancer mortality and other cancer mortality represented different variation laws. Conclusions: Although the total cancer mortality risk is increasing at an accelerated rate, cancer mortality risk in recent born year is decreasing, indicating very important impact of social change on the cancer mortality in rural China. [ABSTRACT FROM AUTHOR]

Electrocaloric is a novel emerging not-in-kind cooling technology based on solid-state materials exhibiting the electrocaloric effect, i.e., the property of changing their temperature because of an adiabatic change in the intensity of the electric field applied. This technology has only attracted the interests of the scientific community in the last two decades, even though it has the main feature of being based on eco-friendly materials that, because of their solid-state nature, do not provide a direct contribution in global warming. Even if some steps have already been taken, the research fields connected to electrocaloric cooling are still open: The identification of the most appropriated thermodynamic cycle, electrocaloric refrigerants, as well as the development of efficient cooling systems. To this purpose, this review paper provides a snapshot of the electrocaloric world and compares the progress made by the inherent scientific community in all the connected fields: the thermodynamic cycles, materials, experimental devices, numerical models, energy performances and prospective cooling applications. [ABSTRACT FROM AUTHOR]

The paper promotes the notion of computational experiment supported by a multi-tool digital environment as a means of the development of new mathematical knowledge in the context of education. The main study of the paper deals with the issues of teaching this knowledge to secondary teacher candidates within a graduate capstone mathematics education course. The interplay of mathematics and education is considered through the lens of using technology to enhance one's mathematical background by advancing ideas from mostly known to genuinely unknown. In this paper, the knowns consist of Fibonacci numbers, Pascal's triangle, and continued fractions; among the unknowns are Fibonacci-like polynomials and generalized golden ratios in the form of cycles of various lengths. The paper discusses the interplay of pragmatic and epistemic uses of digital tools by the learners of mathematics. The data for the study were collected over the years through solicited comments by teacher candidates enrolled in the capstone course. The main results indicate the candidates' appreciation of the need for deep mathematical knowledge as an instrument of the modern-day pedagogy aimed at making high schoolers interested in the subject matter. [ABSTRACT FROM AUTHOR]

The problem of finding bipartite (Tanner) graphs with given degree sequences that have large girth and few short cycles is of great interest in many applications including construction of good low-density parity-check (LDPC) codes. In this paper, we prove that for given integers $\alpha $ , $\beta $ , and $\gamma $ , and degree sequences $\pi $ and $\pi '$ , the problem of determining whether there exists a simple bipartite graph with degree sequences $(\pi, \pi ')$ that has at most $\alpha $ ($\beta $ and $\gamma $) cycles of length four (six and eight, respectively) is NP-complete. This is proved by a two-step polynomial-time reduction from the 3-Partition Problem. On the other hand, using connections to linear hypergraphs, we prove that given the degree sequence $\pi $ , a polynomial time algorithm can be devised to determine whether there exists a bipartite graph whose degree sequence on one side of the bipartition is $\pi $ and has a girth of at least six. In addition to these complexity results, we devise a quasi-polynomial time algorithm that can construct a bipartite graph with given (irregular) degree sequences and a girth that increases logarithmically with the size of the graph. Compared to the well-known progressive-edge-growth (PEG) algorithm, the proposed method, in some cases, results in Tanner graphs with larger girth, particularly for scenarios where the degree sequences of the graph are strictly enforced. [ABSTRACT FROM AUTHOR]

Background: This paper addresses the problem of finding attractors in biological regulatory networks. We focus here on non-deterministic synchronous and asynchronous multi-valued networks, modeled using automata networks (AN). AN is a general and well-suited formalism to study complex interactions between different components (genes, proteins,...). An attractor is a minimal trap domain, that is, a part of the state-transition graph that cannot be escaped. Such structures are terminal components of the dynamics and take the form of steady states (singleton) or complex compositions of cycles (non-singleton). Studying the effect of a disease or a mutation on an organism requires finding the attractors in the model to understand the long-term behaviors. Results: We present a computational logical method based on answer set programming (ASP) to identify all attractors. Performed without any network reduction, the method can be applied on any dynamical semantics. In this paper, we present the two most widespread non-deterministic semantics: the asynchronous and the synchronous updating modes. The logical approach goes through a complete enumeration of the states of the network in order to find the attractors without the necessity to construct the whole state-transition graph. We realize extensive computational experiments which show good performance and fit the expected theoretical results in the literature. Conclusion: The originality of our approach lies on the exhaustive enumeration of all possible (sets of ) states verifying the properties of an attractor thanks to the use of ASP. Our method is applied to non-deterministic semantics in two different schemes (asynchronous and synchronous). The merits of our methods are illustrated by applying them to biological examples of various sizes and comparing the results with some existing approaches. It turns out that our approach succeeds to exhaustively enumerate on a desktop computer, in a large model (100 components), all existing attractors up to a given size (20 states). This size is only limited by memory and computation time. [ABSTRACT FROM AUTHOR]

In this paper we consider the class C of all T-periodic competitive and dissipative 3-dimensional systems which have a cyclic in the boundary and such that the origin is a source. We use the ideas in [1] in order to give a correct proof of theorem 1.2 of [1] where we study the coexistence state for these system. [ABSTRACT FROM AUTHOR]

This paper aims to study the principles and concepts underlying the thermal fatigue modeling under laboratory conditions. The main objective of this paper is to take a decision on laboratory modeling of thermal fatigue that occurs in parts of machines constituting internal combustion engines. Thermal fatigue study under laboratory conditions lead to the thermal fatigue resistance limits for different machine parts in the composition of internal combustion engines, specific to avoid cracking of the engine by optimizing the thermal regime and proposals for new materials with high resistance to thermal fatigue. [ABSTRACT FROM AUTHOR]

This paper explores the implications of observed national housing sector experiences across the advanced economies before, through and out of the 'Great Financial Crash' (GFC) of 2008. The evidence suggests that over-aggregative explanation of these experiences and their broader economic consequences is somewhat misleading; empirical and theoretical explanations to date have largely failed to recognise that housing sectors can play transformative rather than just passive roles in shaping national economic outcomes. In practice, housing volatility, and the implications of this volatility for macroeconomic stability and growth, reflects specific national financial, spatial and policy structures, housing system institutional structures and participant behaviour patterns. In spite of this, the housing policy paradigms that dominated in the decades prior to the GFC remain largely in place, and national housing policy frameworks continue to give insufficient attention to housing system stability and efficiency concerns. Housing research and housing policies need to be reoriented to better address the processes that contributed to the GFC and that more generally continue to shape national economic cycles and growth paths. [ABSTRACT FROM AUTHOR]

The response spectra are helpful to understand the vibrational characteristics of linear system, and further could be used as important indications for the failure diagnosis and state detecting of the system. Due to the parametric excitation, the vibrational spectra of linear periodic system differ distinctly from that of the linear time-invariant system. Thus, utilizing the Sylvester’s theorem and Fourier series approximations, commonly used in the matrix decomposition, the spectral components for both the free and forced responses of linear parametrically excited system are obtained theoretically in the first part of the paper. The effects of system stability and damping on the response spectra are discussed in detail. Moreover, the external resonant condition for periodic system is found in the analysis. In the following part of the paper, spectral simulations for a spur gear pair under idle load (modeled as the free response) and fluctuating load (modeled as forced response) are done respectively to validate the theoretical results and illustrate the special frequency distributing features of periodic system intuitively. [ABSTRACT FROM AUTHOR]

A circulant-permutation-based spatially-coupled (SC) code is constructed by partitioning the circulant permutation matrices (CPMs) in the parity-check matrix of a block code into several components and piecing copies of these components in a diagonal structure. By connecting several SC codes, multi-dimensional SC (MD-SC) codes are constructed. In this paper, we present a systematic framework for constructing MD-SC codes with notably better cycle properties than their one-dimensional counterparts. In our framework, the multi-dimensional coupling is performed via an informed relocation of problematic CPMs. This work is general in the terms of the number of constituent SC codes that are connected together, the number of neighboring SC codes that each constituent SC code is connected to, and the length of the cycles whose populations we aim to reduce. Finally, we present a decoding algorithm that utilizes the structures of the MD-SC code to achieve lower decoding latency. Compared to the conventional SC codes, our MD-SC codes have a notably lower population of small cycles, and a dramatic BER improvement. The results of this work can be particularly beneficial in data storage systems, e.g., 2D magnetic recording and 3D Flash systems, as high-performance MD-SC codes are robust against various channel impairments and non-uniformity. [ABSTRACT FROM AUTHOR]

Since the invention of lithium ion batteries, charging strategies have met great acknowledgment and research over the years. In this paper, a laptop with lithium polymer battery is monitored via three widely used tools, during various operational and charging loads. Several key values are obtained in order to evaluate the correlation between battery cycles, charging percentages and depth of discharge. Ultimately the results show that massive discharges and continuous operation with the device plugged should be avoided, though high load tasks require the AC charger to be connected. Ensuring that battery stays at safe temperature and charging ranges can expand cell life and state, as well as prevent lithium deposits inside the battery. [ABSTRACT FROM AUTHOR]

This paper studies the evolving distribution of prices in a vertical sector in the presence of market cycles. It investigates the dynamic linkages between farm and retail prices with an application to the Chinese pork sector. The econometric approach relies on a quantile autoregressive (QAR) model that provides a flexible representation of the dynamics of price volatility. It investigates the presence and nature of price cycles and their implications for price transmission. We document that the marketing margin is more sensitive to changes in consumer income than in feed cost. In addition, rising feed cost increases the amplitude of the cycle while higher consumer income increases the period of the cycle. [ABSTRACT FROM AUTHOR]

This paper presents a new variant of the vehicle routing problem (VRP), the prize-collecting vehicle routing problem (PCVRP), which is derived from the hot rolling production of the iron and steel industry. One major characteristic of the PCVRP is that the customers need not be visited compulsorily but a prize can be collected from each customer when visited. Besides the capacity constraint, a task completion constraint is introduced and requires that the total demand of the visited customers should be no less than a predetermined amount. The main objective is a linear combination of three objectives: minimization of total distance traveled, minimization of vehicles used, and maximization of prizes collected. An iterated local search algorithm (ILS) based on very large-scale neighborhood (VLSN) using cyclic transfer is proposed for the PCVRP. Computational results of problem instances with up to 100 customers show the algorithm is efficient and effective. [ABSTRACT FROM AUTHOR]

Research has found strong links between past credit booms and adverse outcomes for macroeconomic aggregates like output and investment. However, are price impacts also seen more widely in broad asset classes such as equity and fixed-income markets? We document such a robust and significant connection using a large sample of historical data for many advanced countries since 1870. Credit boom periods with a high "leverage factor" tend to be predictably followed by unusually low returns to risky equities, in absolute terms and relative to a safe fixed-income portfolio. Fixed income is a safe haven at these times and has slightly higher than normal returns. We show these properties hold in-sample and out-of-sample. Return predictability because of the leverage factor is distinct from that because of momentum (lagged return) and value (cashflow relative to price). Trading strategies built on the leverage factor accrue meaningful excess profits out-of-sample. This paper was accepted by Victoria Ivashina, finance. [ABSTRACT FROM AUTHOR]

This article summarizes the main findings on problems related to the measurement and identification of business cycles. The aim of this study is to define and identify the determinants of business cycles. This paper provides an overview of the methodology and its future course. Our investigation suggests that some methodological frameworks are available in the literature, but none is perfect. A new development in the field lies in spectral analysis methods for measuring business cycles, which may have advantages over existing methodologies (nonlinearity, stationarity issues). We feel that fractional integration is important in the proper monitoring and explanation of business cycles. Spectral analysis techniques have also proved to be useful for addressing the problems of stationarity and structural breaks in time series when analyzing business cycles. Another important issue that is excluded when studying business cycles is that the link between cycles and economic growth is presumed to be non-existent, implying money neutrality. [ABSTRACT FROM AUTHOR]

Purpose Credit market models and the microstructure theory of the ratings market suggest that information provided by credit rating agencies becomes more relevant in recessions when agency costs are high and less relevant in expansions when agency costs are low. The purpose of this paper is to empirically test these hypotheses with regard to equity markets.Design/methodology/approach The authors use business cycle identification algorithms to map rating events (credit rating changes and watchlist inclusions) to business cycle phases and apply the event study methodology. The results are backed by cross-sectional regressions using a variety of control variables.Findings The authors find that the relevance of information provided by credit rating agencies for equity prices heavily depends on the level of agency costs. Furthermore, the authors detect a “flight-to-quality” during recessions in the speculative grade segment and a weakened relevance of rating events in expansions in the investment grade segment.Originality/value This paper is the first to empirically analyse how equity investors perceive credit rating changes and watchlist inclusions over the business cycle. In the empirical analysis, the authors use a large sample of about 25,000 rating events in all Organisation for Economic Co-operation and Development markets. The presented results underline that credit ratings address the agency problem in financial markets and can thus be regarded as useful for risk management or regulation. [ABSTRACT FROM AUTHOR]

Due to the recent explosive growth of location-aware services based on mobile devices, predicting the next places of a user is of increasing importance to enable proactive information services. In this paper, we introduce a data-driven framework that aims to predict the user's next places using his/her past visiting patterns analyzed from mobile device logs. Specifically, the notion of the spatiotemporal-periodic (STP) pattern is proposed to capture the visits with spatiotemporal periodicity by focusing on a detail level of location for each individual. Subsequently, we present algorithms that extract the STP patterns from a user's past visiting behaviors and predict the next places based on the patterns. The experiment results obtained by using a real-world dataset show that the proposed methods are more effective in predicting the user's next places than the previous approaches considered in most cases. [ABSTRACT FROM AUTHOR]

Epilepsy is characterized by recurrent, unprovoked seizures. Accurate prediction of seizure occurrence has long been a clinical goal since this would allow to optimize patient treatment, prevent injuries due to seizures, and alleviate the patient burden of unpredictability. Advances in implantable electroencephalographic (EEG) devices, allowing for long-term interictal EEG recordings, have facilitated major progress in this field. Recently, it has been discovered that interictal brain activity demonstrates circadian and multi-dien cycles that are strongly aligned, or phase locked, with seizure risk. Thus, cyclical brain activity patterns have been used to forecast seizures. However, in the effort to develop a clinically useful EEG based seizure forecasting system, challenges remain. Firstly, multiple EEG features demonstrate cyclical patterns, but it remains unclear which feature is best suited for predicting seizures. Secondly, the technology for long-term EEG recording is currently limited in both spatial and temporal sampling resolution. In this study, we compare five established EEG metrics:synchrony, spatial correlation, temporal correlation, signal variance which have been motivated from critical dynamics theory, and interictal epileptiform discharge (IED) which are a traditional marker of seizure propensity. We assess their effectiveness in detecting 24-h and seizure cycles as well as their robustness under spatial and temporal subsampling. Analyzing intracranial EEG data from 23 patients, we report that all examined features exhibit 24-h cycles. Spatial correlation, signal variance, and synchrony showed the highest phase locking with seizures, while IED rates were the lowest. Notably, spatial and temporal correlation were also found to be highly correlated to each other, as were signal variance and IED--suggesting some features may reflect similar aspects of cortical dynamics, whereas others provide complementary information. All features proved robust under subsampling, indicating that the dynamic properties of interictal activity evolve slowly and are not confined to specific brain regions. Our results may aid future translational research by assisting in design and testing of EEG based seizure forecasting systems. [ABSTRACT FROM AUTHOR]