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Articles de revues sur le sujet « Symmetric products of curves »

Auteur : Grafiati
Publié le 9 mars 2023
Mis à jour le 10 mars 2023

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1

Harris, Joe, et Joe Silverman. « Bielliptic curves and symmetric products ». Proceedings of the American Mathematical Society 112, no 2 (1 février 1991) : 347. http://dx.doi.org/10.1090/s0002-9939-1991-1055774-0.

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Bastianelli, F. « On symmetric products of curves ». Transactions of the American Mathematical Society 364, no 5 (1 mai 2012) : 2493–519. http://dx.doi.org/10.1090/s0002-9947-2012-05378-5.

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Biswas, Indranil, et Shane D’Mello. « M-curves and symmetric products ». Proceedings - Mathematical Sciences 127, no 4 (3 août 2017) : 615–24. http://dx.doi.org/10.1007/s12044-017-0347-2.

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Kouvidakis, Alexis. « Divisors on symmetric products of curves ». Transactions of the American Mathematical Society 337, no 1 (1 janvier 1993) : 117–28. http://dx.doi.org/10.1090/s0002-9947-1993-1149124-5.

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Ross, J. « Seshadri constants on symmetric products of curves ». Mathematical Research Letters 14, no 1 (2007) : 63–75. http://dx.doi.org/10.4310/mrl.2007.v14.n1.a5.

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Vanhaecke, Pol. « Integrable systems and symmetric products of curves ». Mathematische Zeitschrift 227, no 1 (janvier 1998) : 93–127. http://dx.doi.org/10.1007/pl00004370.

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MEJÍA, ISRAEL MORENO. « CHARACTERISTIC CLASSES ON SYMMETRIC PRODUCTS OF CURVES ». Glasgow Mathematical Journal 46, no 3 (septembre 2004) : 477–88. http://dx.doi.org/10.1017/s0017089504001946.

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Wang, Zhi Lan. « Tautological integrals on symmetric products of curves ». Acta Mathematica Sinica, English Series 32, no 8 (15 juillet 2016) : 901–10. http://dx.doi.org/10.1007/s10114-016-5565-5.

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Krug, Andreas. « Stability of tautological bundles on symmetric products of curves ». Mathematical Research Letters 27, no 6 (2020) : 1785–800. http://dx.doi.org/10.4310/mrl.2020.v27.n6.a9.

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Elencwajg, Georges. « Brauer group of fibrations and symmetric products of curves ». Proceedings of the American Mathematical Society 94, no 4 (1 avril 1985) : 597. http://dx.doi.org/10.1090/s0002-9939-1985-0792268-9.

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Franz, Matthias. « Symmetric Products of Equivariantly Formal Spaces ». Canadian Mathematical Bulletin 61, no 2 (1 juin 2018) : 272–81. http://dx.doi.org/10.4153/cmb-2017-032-0.

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AbstractLet X be a CW complex with a continuous action of a topological group G. We show that if X is equivariantly formal for singular cohomology with coefficients in some field , then so are all symmetric products of X and in fact all its Γ-products. In particular, symmetric products of quasi-projective M-varieties are again M-varieties. This generalizes a result by Biswas and D’Mello about symmetric products of M-curves. We also discuss several related questions.
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Aprodu, Marian, et Edoardo Sernesi. « Excess dimension for secant loci in symmetric products of curves ». Collectanea Mathematica 68, no 1 (12 février 2016) : 1–7. http://dx.doi.org/10.1007/s13348-016-0166-2.

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Bastianelli, F. « Remarks on the nef cone on symmetric products of curves ». manuscripta mathematica 130, no 1 (5 mai 2009) : 113–20. http://dx.doi.org/10.1007/s00229-009-0274-3.

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CILIBERTO, CIRO, et MIKHAIL ZAIDENBERG. « 3-FOLD SYMMETRIC PRODUCTS OF CURVES AS HYPERBOLIC HYPERSURFACES IN ℙ4 ». International Journal of Mathematics 14, no 04 (juin 2003) : 413–36. http://dx.doi.org/10.1142/s0129167x0300182x.

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We construct new examples of Kobayashi hyperbolic hypersurfaces in ℙ4. They are generic projections of the triple symmetric product V = C (3) of a generic genus g ≥ 6 curve C, smoothly embedded in ℙ7.
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HASSETT, BRENDAN, et YURI TSCHINKEL. « ABELIAN FIBRATIONS AND RATIONAL POINTS ON SYMMETRIC PRODUCTS ». International Journal of Mathematics 11, no 09 (décembre 2000) : 1163–76. http://dx.doi.org/10.1142/s0129167x00000544.

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Given a variety over a number field, are its rational points potentially dense, i.e. does there exist a finite extension over which rational points are Zariski dense? We study the question of potential density for symmetric products of surfaces. Contrary to the situation for curves, rational points are not necessarily potentially dense on a sufficiently high symmetric product. Our main result is that rational points are potentially dense for the Nth symmetric product of a K3 surface, where N is explicitly determined by the geometry of the surface. The basic construction is that for some N, the Nth symmetric power of a K3 surface is birational to an Abelian fibration over ℙN. It is an interesting geometric problem to find the smallest N with this property.
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Biswas, Indranil, Tomás Gómez et Kyoung-Seog Lee. « Semi-orthogonal decomposition of symmetric products of curves and canonical system ». Revista Matemática Iberoamericana 37, no 5 (16 février 2021) : 1885–96. http://dx.doi.org/10.4171/rmi/1251.

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du Sautoy, Marcus. « Natural boundaries for Euler products of Igusa zeta functions of elliptic curves ». International Journal of Number Theory 14, no 08 (22 août 2018) : 2317–31. http://dx.doi.org/10.1142/s1793042118501415.

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We study the analytic behavior of adelic versions of Igusa integrals given by integer polynomials defining elliptic curves. By applying results on the meromorphic continuation of symmetric power L-functions and the Sato–Tate conjectures, we prove that these global Igusa zeta functions have some meromorphic continuation until a natural boundary beyond which no continuation is possible.
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Ciliberto, Ciro, et Edoardo Sernesi. « On the symmetric products of a curve ». Archiv der Mathematik 61, no 3 (septembre 1993) : 285–90. http://dx.doi.org/10.1007/bf01198726.

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Silverman, Joseph H. « Rational Points on Symmetric Products of a Curve ». American Journal of Mathematics 113, no 3 (juin 1991) : 471. http://dx.doi.org/10.2307/2374836.

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DE OLIVERA, FEDERICO, JOSÉ FAJARDO et ERNESTO MORDECKI. « SKEWED LÉVY MODELS AND IMPLIED VOLATILITY SKEW ». International Journal of Theoretical and Applied Finance 21, no 02 (mars 2018) : 1850003. http://dx.doi.org/10.1142/s0219024918500036.

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We introduce skewed Lévy models, characterized by a symmetric jump measure multiplied by a damping exponential factor. These models exhibit a clear implied volatility pattern, where the damping parameter controls the implied volatility curve’s skew, resulting in a measure of the model’s skewness. We show that the variation of this parameter produces the typical smirk observed in implied volatility curves. Some theoretical facts supporting these findings are proved.
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21

Pacienza, Gianluca. « On the nef cone of symmetric products of a generic curve ». American Journal of Mathematics 125, no 5 (2003) : 1117–35. http://dx.doi.org/10.1353/ajm.2003.0034.

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Baird, Thomas John. « Symmetric products of a real curve and the moduli space of Higgs bundles ». Journal of Geometry and Physics 126 (mars 2018) : 7–21. http://dx.doi.org/10.1016/j.geomphys.2018.01.003.

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Askar, S. S. « On Complex Dynamics of Differentiated Products : Cournot Duopoly Model under Average Profit Maximization ». Discrete Dynamics in Nature and Society 2022 (9 mars 2022) : 1–14. http://dx.doi.org/10.1155/2022/8677470.

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In this paper, some important dynamic characteristics such as multistability and synchronization phenomena are investigated for a game of an economic Cournot duopoly whose time evolution is received by the iteration of a noninvertible map in the plane. In the asymmetric case, the equilibrium points of game’s map are calculated, and their stability conditions are obtained. The obtained results show that the Nash equilibrium point loses its stability through flip bifurcation. Under some restrictions, the map’s coordinate axes form an invariant manifold, and hence their dynamics are studied based on a one-dimensional discrete dynamic map. In the symmetric case where both firms are identical, the map has the property of symmetry, and this implies that the diagonal q 1 = q 2 forms an invariant manifold and therefore synchronization phenomena occur. Global analysis of the behavior of the noninvertible map is carried out through studying critical manifolds of the map that categorize it as Z 4 − Z 2 − Z 0 type. Furthermore, global bifurcation of the basins of attraction is confirmed through contact between the critical curves and the boundaries of escaping domain.
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KAMENSHCHIK, ALEXANDER YU, et ISAAK M. KHALATNIKOV. « SOME PROPERTIES OF THE "STRING GAS" WITH THE EQUATION OF STATE $p = -\frac{1}{3} \rho$ ». International Journal of Modern Physics D 21, no 01 (janvier 2012) : 1250004. http://dx.doi.org/10.1142/s0218271812500046.

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We show that the string gas — a perfect fluid with the equation of state [Formula: see text] possesses rather interesting properties. In Friedmann universes its presence can change the observable topology of the space; in the spherically symmetric spacetimes it produces rather bizzare geometries and in a way its influence on the rotation curves mimics the dark matter effects.
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SCHERFF, PHILLIP-CHRISTOPH, GEORGE BACIU et JINLIAN HU. « INTUITIVE PARAMETERIZED INPUT INTERFACE FOR PROPORTIONAL RESHAPING OF HUMAN BODIES ». International Journal of Image and Graphics 08, no 02 (avril 2008) : 299–325. http://dx.doi.org/10.1142/s0219467808003106.

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In the computer world garment products need to be simulated on different virtual human bodies. In this paper we are going to change virtual human actors in a proportional way. As part of the work we design a user-friendly interface for a more intuitive input of body parameters. Curves, implemented as NURBS, create an effective/easy input method for the proportional reshaping task. Implementation of an automatic approach for computing an underlying skeleton was done, which enables us to reshape a virtual human. As body proportions are difficult to define, this paper researches on artistic methods to describe the symmetric and harmonious structures of human bodies. A flexible data structure is employed in order to traverse and access regional information efficiently. As a main goal of this work we designed a high level controller for body parts enabling proportional reshaping.
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Tang, Anisia P. S., et K. S. Cheng. « Thermal X-Ray Pulses Resulting From Pulsar Glitches ». International Astronomical Union Colloquium 177 (2000) : 441–42. http://dx.doi.org/10.1017/s0252921100060255.

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AbstractThe non-spherical symmetric and exact thermal evolution model is used to calculate the transient thermal response to pulsar glitches. The three ways of energy release originated from glitches, namely the ‘shell’, ‘ring’ and ‘spot’ cases are compared. The ‘ring’ case is always the middle one in terms of the response time, the response duration and the intensity of the response. Taking the relativistic light bending effect and the rotational effect into consideration, the X-ray light curves resulting from the thermal response to the glitches are calculated. Only the ‘spot’ case produces modulative X-rays. Different sets of parameters result in different evolution patterns of light curves. This is thus a good method to determine the equations of state for pulsars.
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Pang, Jihong, Jinkun Dai, Chaohui Zhang, Hongyong Zhou et Yong Li. « A New Dynamic Fault Tree Analysis Method of Electromagnetic Brakes Based on Bayesian Network Accompanying Wiener Process ». Symmetry 14, no 5 (9 mai 2022) : 968. http://dx.doi.org/10.3390/sym14050968.

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Product fault diagnosis has always been the focus of quality and reliability research. However, a failure–rate curve of some products is a symmetrical function, the fault analysis result is not true because the failure period of the products cannot be judged accurately. In order to solve the problem of fault diagnosis, this paper proposes a new Takagi-Sugeno (T-S) dynamic fault tree analysis method based on a Bayesian network accompanying the Wiener process. Firstly, the top event, middle event, and bottom event of the product failure mode are determined, and the T-S dynamic fault tree is constructed. Secondly, in order to form the Bayesian network diagram of the T-S dynamic fault tree, the events in the fault tree are transformed into nodes, and the T-S dynamic gate is also transformed into directed edges. Then, the Wiener process is used to model the performance degradation process of the stationary independent increment of the symmetric function distribution, and the maximum likelihood estimation method is applied to estimate the unknown parameters of the degradation model. Next, the product residual life prediction model is established based on the concept of first arrival time, and a symmetric function of failure–rate curve is obtained by using the product failure probability density function. According to the fault density function derived from the Wiener process, the reverse reasoning algorithm of the Bayesian network is established. Combined with the prior probability of the bottom event, the posterior probability of the root node is calculated and sorted as well. Finally, taking the insufficient braking force of electromagnetic brakes as an example, the practicability and objectivity of the new method are proved.
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Spitzer, Emily R., et Michelle L. Hughes. « Effect of Stimulus Polarity on Physiological Spread of Excitation in Cochlear Implants ». Journal of the American Academy of Audiology 28, no 09 (octobre 2017) : 786–98. http://dx.doi.org/10.3766/jaaa.16144.

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AbstractContemporary cochlear implants (CIs) use cathodic-leading, symmetrical, biphasic current pulses, despite a growing body of evidence that suggests anodic-leading pulses may be more effective at stimulating the auditory system. However, since much of this research on humans has used pseudomonophasic pulses or biphasic pulses with unusually long interphase gaps, the effects of stimulus polarity are unclear for clinically relevant (i.e., symmetric biphasic) stimuli.The purpose of this study was to examine the effects of stimulus polarity on basic characteristics of physiological spread-of-excitation (SOE) measures obtained with the electrically evoked compound action potential (ECAP) in CI recipients using clinically relevant stimuli.Using a within-subjects (repeated measures) design, we examined the differences in mean amplitude, peak electrode location, area under the curve, and spatial separation between SOE curves obtained with anodic- and cathodic-leading symmetrical, biphasic pulses.Fifteen CI recipients (ages 13–77) participated in this study. All were users of Cochlear Ltd. devices.SOE functions were obtained using the standard forward-masking artifact reduction method. Probe electrodes were 5–18, and they were stimulated at an 8 (of 10) loudness rating (“loud”). Outcome measures (mean amplitude, peak electrode location, curve area, and spatial separation) for each polarity were compared within subjects.Anodic-leading current pulses produced ECAPs with larger average amplitudes, greater curve area, and less spatial separation between SOE patterns compared with that for cathodic-leading pulses. There was no effect of polarity on peak electrode location.These results indicate that for equal current levels, the anodic-leading polarity produces broader excitation patterns compared with cathodic-leading pulses, which reduces the spatial separation between functions. This result is likely due to preferential stimulation of the central axon. Further research is needed to determine whether SOE patterns obtained with anodic-leading pulses better predict pitch discrimination.
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CONTOPOULOS, G., et M. HARSOULA. « STICKINESS IN CHAOS ». International Journal of Bifurcation and Chaos 18, no 10 (octobre 2008) : 2929–49. http://dx.doi.org/10.1142/s0218127408022172.

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We distinguish two types of stickiness in systems of two degrees of freedom: (a) stickiness around an island of stability, and (b) stickiness in chaos, along the unstable asymptotic curves of unstable periodic orbits. In fact, there are asymptotic curves of unstable orbits near the outer boundary of an island that remain close to the island for some time, and then extend to large distances into the surrounding chaotic sea. But later the asymptotic curves return close to the island and contribute to the overall stickiness that produces dark regions around the islands and dark lines extending far from the islands. We have studied these effects in the standard map with a rather large nonlinearity K = 5, and we emphasized the role of the asymptotic curves U , S from the central orbit O (x = 0.5, y = 0), that surround two large islands O 1 and O ′1, and the asymptotic curves U + U - S + S - from the simplest unstable orbit around the island O 1. This is the orbit 4/9 that has 9 points around the island O 1 and 9 more points around the symmetric island O ′1. The asymptotic curves produce stickiness in the positive time direction ( U , U +, U -) and in the negative time direction ( S , S +, S -). The asymptotic curves U +, S + are closer to the island O 1 and make many oscillations before reaching the chaotic sea. The curves U -, S - are further away from the island O 1 and escape faster. Nevertheless all curves return many times close to O 1 and contribute to the stickiness near this island. The overall stickiness effects of U +, U - are very similar and the stickiness effects along S +, S - are also very similar. However, the stickiness in the forward time direction, along U +, U -, is very different from the stickiness in the opposite time direction along S +, S -. We calculated the finite time LCN (Lyapunov characteristic number) χ( t ), which is initially smaller for U +, S + than for U -, S -. However, after a long time all the values of χ( t ) in the chaotic zone approach the same final value LCN = lim t → ∞ χ(t). The stretching number (LCN for one iteration only) varies along an asymptotic curve going through minima at the turning points of the asymptotic curve. We calculated the escape times (initial stickiness times) for many initial points outside but close to the island O 1. The lines that separate the regions of the fast from the slow escape time follow the shape of the asymptotic curves S +, S -. We explained this phenomenon by noting that lines close to S + on its inner side (closer to O 1) approach a point of the orbit 4/9, say P 1, and then follow the oscillations of the asymptotic curve U +, and escape after a rather long time, while the curves outside S + after their approach to P 1 follow the shape of the asymptotic curves U - and escape fast into the chaotic sea. All these curves return near the original arcs of U +, U - and contribute to the overall stickiness close to U +, U -. The isodensity curves follow the shape of the curves U +, U - and the maxima of density are along U +, U -. For a rather long time, the stickiness effects along U +, U - are very pronounced. However, after much longer times (about 1000 iterations) the overall stickiness effects are reduced and the distribution of points in the chaotic sea outside the islands tends to be uniform. The stickiness along the asymptotic curve U of the orbit O is very similar to the stickiness along the asymptotic curves U +, U - of the orbit 4/9. This is related to the fact that the asymptotic curves of O and 4/9 are connected by heteroclinic orbits. However, the main reason for this similarity is the fact that the asymptotic curves U , U +, U - cannot intersect but follow each other.
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Wang, Yi, Baoying Wang, Yang Liu et Yongtu Liang. « Study on Asymmetry Concentration of Mixed Oil in Products Pipeline ». Energies 13, no 23 (3 décembre 2020) : 6398. http://dx.doi.org/10.3390/en13236398.

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Long-distance pipelines transporting multiple product oils such as gasoline, diesel and jet fuel, are important facilities for transporting fossil energy. One major concern in operation is the energy consumption of the pipeline. Energy consumption should be made optimized tracking batches of oils and cutting mixed oil, which requires an accurate prediction of concentration curve. In engineering, the concentration curve is usually assumed to be symmetric, but it is actually asymmetric, which may lead to estimation errors. Thus, the asymmetric concentration of mixed oil should be studied. The formation mechanism of the asymmetry of concentration curve has not been clearly clarified. A new method is proposed to measure the asymmetry of the concentration curve. Quantitative analysis is carried out for each factor on the asymmetry distribution of concentration curve. Based on the convection–diffusion equation, a modified oil-mixing model considering near wall adsorption effect is established. The model shows a good agreement with the Jablonski empirical formula. The error, compared with the experimental results, is less than 5%. The main findings are: (1) deviation volume has a negative correlation with pipe diameter and mean velocity; (2) adsorption coefficient has a greater impact on the length ratio of front and tail oil than diffusion coefficient; (3) the influence of all factors considered on the total length of mixed oil, front oil, tail oil and trail oil are basically the same; (4) if the limit of adsorption concentration in adsorption layer is 1, the reasonable value of adsorption coefficient a and b should be around 0.4. The results reveal the mechanism of asymmetric concentration of product oils and can provide practical suggestions to deal with the mixed oil.
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Klimenko, Stanislav, Igor Nikitin et Lialia Nikitina. « Numerical solutions of Einstein field equations with radial dark matter ». International Journal of Modern Physics C 28, no 07 (juillet 2017) : 1750096. http://dx.doi.org/10.1142/s0129183117500966.

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We study a static spherically symmetric problem with a black hole and radially directed geodesic flows of dark matter. The obtained solutions have the following properties. At large distances, the gravitational field produces constant velocities of circular motion, i.e. flat rotation curves. At smaller distances, the field switches to Newtonian regime, then to Schwarzschild regime. Deviations from Schwarzschild regime start below the gravitational radius. The dark matter prevents the creation of event horizon, instead, a spherical region possessing extremely large redshift is created. The structure of space-time for the obtained solutions is investigated and the implications for the models of the galaxies are discussed.
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Glahn, Bob. « A Nonsymmetric Logit Model and Grouped Predictand Category Development ». Monthly Weather Review 142, no 8 (1 août 2014) : 2991–3002. http://dx.doi.org/10.1175/mwr-d-13-00300.1.

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Abstract Logistic regression is an alternative to regression estimation of event probabilities (REEP) and other techniques for estimating weather event probabilities based on NWP output or other predictors. Logistic regression has the advantage over REEP in that the probability estimates are constrained between zero and unity, whereas REEP can “overshoot” these values. It may be a detriment in some applications that the curves developed, one for each of several predictand categories (events), are symmetric. This paper shows how the logit curve can easily be made nonsymmetric as a function of a predictor, and thereby possibly achieve a better fit to the data. As with REEP, the probabilities estimated by logistic regression for each of several categories of a variable may not be consistent. For instance, the probability of snow > 2 in. may exceed the probability of snow > 1 in. Such inconsistencies can be avoided by developing a single equation involving all predictand categories and including another predictor that is a function of the predictand. This effectively, for a single predictor, produces parallel curves separated along the predictor axis but imposes restrictions on the equations and probabilities produced from them. The relationship between the predictor(s) and the predictand must be considered in determining the functional form. With only one predictor, defining the function is relatively straightforward. However, with multiple predictors, the process is more problematic. This paper demonstrates an alternative to imposing a functional form by using binary predictors. This formulation also achieves the goal of producing consistent forecasts and generalizes more readily to multiple predictors.
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Capuano, Ana W., Robert S. Wilson, Sue E. Leurgans, Jeffrey D. Dawson, David A. Bennett et Donald Hedeker. « Sigmoidal mixed models for longitudinal data ». Statistical Methods in Medical Research 27, no 3 (28 avril 2016) : 863–75. http://dx.doi.org/10.1177/0962280216645632.

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Linear mixed models are widely used to analyze longitudinal cognitive data. Often, however, the trajectory of cognitive function is nonlinear. For example, some participants may experience cognitive decline that accelerates as death approaches. Polynomial regression and piecewise linear models are common approaches used to characterize nonlinear trajectories, although both have assumptions that may not correspond with the actual trajectories. An alternative is to use a flexible sigmoidal mixed model based on the logistic family of curves. We describe a general class of such a model, which has up to five parameters, representing (1) final level, (2) rate of decline, (3) midpoint of decline, (4) initial level before decline, and (5) asymmetry. Focusing on a four-parameter symmetric sub-class of the model, with random effects on two of the parameters, we demonstrate that a likelihood approach to fitting this model produces accurate estimates of mean levels across time, even in the case of model misspecification. We also illustrate the method on deceased participants who had completed at least 5 years of annual cognitive testing and annual assessment of body mass. We show that departures from a stable body can modify the trajectory curves and anticipate cognitive decline.
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Landi, Giovanni, Luca La Notte, Alessandro Lorenzo Palma, Andrea Sorrentino, Maria Grazia Maglione et Giovanni Puglisi. « A Comparative Evaluation of Sustainable Binders for Environmentally Friendly Carbon-Based Supercapacitors ». Nanomaterials 12, no 1 (24 décembre 2021) : 46. http://dx.doi.org/10.3390/nano12010046.

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Environmentally friendly energy storage devices have been fabricated by using functional materials obtained from completely renewable resources. Gelatin, chitosan, casein, guar gum and carboxymethyl cellulose have been investigated as sustainable and low-cost binders within the electrode active material of water-processable symmetric carbon-based supercapacitors. Such binders are selected from natural-derived materials and industrial by-products to obtain economic and environmental benefits. The electrochemical properties of the devices based on the different binders are compared by using cyclic voltammetry, galvanostatic charge/discharge curves and impedance spectroscopy. The fabricated supercapacitors exhibit series resistance lower than a few ohms and values of the specific capacitance ranged between 30 F/g and 80 F/g. The most performant device can deliver ca. 3.6 Wh/kg of energy at a high power density of 3925 W/kg. Gelatin, casein and carboxymethyl cellulose-based devices have shown device stability up to 1000 cycles. Detailed analysis on the charge storage mechanisms (e.g., involving faradaic and non-faradaic processes) at the electrode/electrolyte interface reveals a pseudocapacitance behavior within the supercapacitors. A clear correlation between the electrochemical performances (e.g., cycle stability, capacitance retention, series resistance value, coulombic efficiency) ageing phenomena and charge storage mechanisms within the porous carbon-based electrode have been discussed.
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35

Zhou, Jianhui, Chuanshuang Hu, Xiaoying Ma et Xingwei Guo. « Finite element modeling and experimental validation of radio frequency heating (RFH) of curved laminated wood-based panels ». Holzforschung 68, no 6 (1 août 2014) : 699–705. http://dx.doi.org/10.1515/hf-2013-0199.

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Abstract Thin medium-density fiberboards (MDF) are often used for the production of curved laminated furniture components by post-hot pressing with radiofrequency heating (RFH). Dimensional instability is one of the major quality problems of these products, and inappropriate heating process was discussed as the main reason for this. In the present study, a finite element model (FEM) was developed in this context, and the temperature distribution within laminated MDF panels was predicted aiming at optimizing the hot-pressing process with RFH. The time-dependent temperatures were collected by temperature sensing strips (TSS). The results agreed well with those obtained by the simulation model. Accordingly, the FEM developed here is well suited for predicting the heating behavior during hot pressing with RFH. The temperature distribution of the curved laminated MDF panels was not symmetric and not uniform because of curved shape effects and the heat convection between MDF panels and ambient air. The time-dependent temperatures of the top and bottom layers were lower than that of the core layer.
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Qiu, L. P., En Chun Zhu, Hua Zhang Zhou et L. Y. Liu. « Fracture Toughness of Northeast China Larch ». Key Engineering Materials 517 (juin 2012) : 661–68. http://dx.doi.org/10.4028/www.scientific.net/kem.517.661.

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Wood, as a green and environment-friendly building material, is widely used in building engineering. Naturally grown, wood has various defects like knots, cracks and inclined grain. Fracture Mechanics is thus an efficient tool to investigate the mechanical behavior of wood and wood-based composite products. According to Linear-elastic Fracture Mechanics (LEFM), fracture toughness can be introduced to measure the resistance to crack propagation. Crack was assumed to occur when the stress intensity factorKreached a critical valueKC.Fracture in wood usually involves not only the Mode I type (open) fracture, but also the Mode II type (shear) fracture. For getting a better understanding of the crack growth phenomenon of Northeast China Larch, it is, therefore, essential to assess theKICandKIIC, which are the critical stress intensity factors for Mode I and Mode II type fracture, respectively. In the current study,KICandKIIC, of Northeast China Larch were determined through tests with compact tension specimens and tests with compact symmetric shear specimens, respectively. In addition, the material properties tests were also performed. All of the specimens were cut from the same batch of Glulam beams. Based on the obtained data from experiments, LEFM was employed to explain the fracture failure in the form of crack propagation. Using Extended Finite Element Method (XFEM), simulation of the crack propagation in Mode I and Mode II was performed incorporating ABAQUS. The crack propagation and the load-displacement curves of numerical simulation were in good agreement with experiments, which validated that the proposed numerical approach is suitable for analysis of crack growth in the specimens. As part of a larger program to investigate the fracture behavior of Glulam beams made of Northeast China Larch, this study provides the material properties and validation of the numerical simulation approach. A series of experiments of full-size curved Glulam beams subject to bending and the corresponding simulations extending the numerical approach of this study to the cases of full-size wood composite members are under development.
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Jang, Changuk, Juhong Han, Akshita Maradapu Vera Venkata Sai, Yingshu Li et Okyeon Yi. « A Study on Scalar Multiplication Parallel Processing for X25519 Decryption of 5G Core Network SIDF Function for mMTC IoT Environment ». Wireless Communications and Mobile Computing 2022 (6 juin 2022) : 1–17. http://dx.doi.org/10.1155/2022/4087816.

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When 5G telecommunication becomes a standardized and widely used communication medium, it must be implemented in coherence with certain 5G network standards and requirements. One such requirement is a Subscription Concealed Identifier called SUCI. SUCI prevents the exposure of international mobile subscriber identity (IMSI), which was a vulnerability in previous generation mobile telecommunication networks. Unlike IMSI, SUCI is encrypted and transmitted using a symmetric key cryptographic algorithm, to prevent the aforementioned vulnerabilities. However, for the first terminal to be encrypted, it is necessary to exchange a key with the home network, and this key exchange for SUCI encryption is performed through the Elliptic Curve Integrated Encryption Scheme (ECIES) key exchange algorithm, which is a public-key encryption scheme. However, ECIES uses more computing resources compared to a symmetric key cryptographic algorithm. Additionally, for 5G Subscriber Identity Deconcealing Function (SIDF) to satisfy the massive machine-type communication (mMTC) requirements of 5G, it is necessary to decrypt at least a million SUCIs within a short time. This puts a great burden on the 5G home network to provide the mMTC service for IoT. Therefore, in this paper, we propose a method of constructing 5G SIDF in an mMTC IoT environment. A key method of the proposed 5G SIDF configuration is the use of GPUs. This proposal was aimed at reducing the load in the mMTC environment by performing parallel processing of all cryptographic operations performed in the SIDF using a GPU. In particular, we focused on parallelization of public-key encryption algorithms. In addition, we also compared the method proposed in this paper through a survey of various 5G security products.
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Prodan, Maria, Emilian Ghicioi, Robert Laszlo, Irina Nalboc, Sonia Suvar et Aurelian Nicola. « Experimental and Numerical Study of Ignition and Flame Propagation for Methane–Air Mixtures in Small Vessels ». Processes 9, no 6 (4 juin 2021) : 998. http://dx.doi.org/10.3390/pr9060998.

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Methane is one of the most common gaseous fuels that also exist in nature as the main part of the natural gas, the flammable part of biogas or as part of the reaction products from biomass pyrolysis. In this respect, the biogas and biomass installations are always subjected to explosion hazards due to methane. Simple methods for evaluating the explosion hazards are of great importance, at least in the preliminary stage. The paper describes such a method based on an elementary analysis of the cubic law of pressure rise during the early stages of flame propagation in a symmetrical cylindrical vessel of small volume (0.17 L). The pressure–time curves for lean, stoichiometric and rich methane–air mixtures were recorded and analyzed. From the early stages of pressure–time history, when the pressure increase is equal to or less than the initial pressure, normal burning velocities were evaluated and discussed. Qualitative experiments were performed in the presence of a radioactive source of 60Co in order to highlight its influence over the explosivity parameters, such as minimum ignition energy, maximum rate of pressure rise, maximum explosion pressure and normal burning velocity. The results are in agreement with the literature data.
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39

Mukai, Shigeru. « Curves and symmetric spaces ». Proceedings of the Japan Academy, Series A, Mathematical Sciences 68, no 1 (1992) : 7–10. http://dx.doi.org/10.3792/pjaa.68.7.

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van Opstall, Michael, et Răzvan Veliche. « Maximally symmetric stable curves ». Michigan Mathematical Journal 55, no 3 (décembre 2007) : 513–34. http://dx.doi.org/10.1307/mmj/1197056455.

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RAY, KUMAR S., et BIMAL KUMAR RAY. « POLYGONAL APPROXIMATION OF DIGITAL CURVE BASED ON REVERSE ENGINEERING CONCEPT ». International Journal of Image and Graphics 13, no 04 (octobre 2013) : 1350017. http://dx.doi.org/10.1142/s0219467813500174.

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This paper applies reverse engineering on the Bresenham's line drawing algorithm [J. E. Bresenham, IBM System Journal, 4, 106–111 (1965)] for polygonal approximation of digital curve. The proposed method has a number of features, namely, it is sequential and runs in linear time, produces symmetric approximation from symmetric digital curve, is an automatic algorithm and the approximating polygon has the least non-zero approximation error as compared to other algorithms.
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42

Ozawa, Fumisato, Kazuki Koyama, Shota Azuma, Tatsuo Horiba et Morihiro Saito. « Analysis of Li Dissolution/Deposition Behavior in LiNO3 Electrolytic Solution for Li-Air Battery ». ECS Meeting Abstracts MA2022-02, no 4 (9 octobre 2022) : 551. http://dx.doi.org/10.1149/ma2022-024551mtgabs.

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Li-air batteries (LAB) have been attracting much attention because of their theoretical energy density of 3500 Wh kg−1, which is five times as high as that of Li-ion batteries. However, many problems remain to be challenged in every component of the battery: air electrodes, electrolytic solutions, Li electrodes, etc. As for the Li electrode, we have reported some results on the reversibility of the Li dissolution/deposition reaction by using Li | Li symmetric cells with tetraglyme (G4) -based electrolytic solution [1, 2]. In particular, it has been confirmed that in the 1.0 M LiNO3/G4 electrolyte under an O2 atmosphere, a Li2O protective layer is efficiently formed on the Li electrode at a current density of 0.4 mA cm-2, and Li dendrite formation is suppressed. In this study, we expanded test conditions in current densities up to 2.0 mA cm-2 and temperatures at 10 °C to 50 °C to reveal whole picture of dissolution/deposition behavior of the Li electrode. A Li | Li symmetric cell was assembled using a pair of Li foils inserted by a separator (Celgard 2400) and 1.0 M LiNO3/G4 or 1.0 M LiTFSI / G4 as the electrolytic solutions in an Ar-filled glove box. The Li dissolution/deposition cycle tests by the cells were carried out at 10, 30 and 50℃ at a constant current density between 0.2 to 2.0 mA cm-2 regulated by a constant capacity of 0.5 mAh cm− 2. After the tests, the Li electrodes were taken out of the cells followed by rinsing in G4 in the glove box, the surfaces of which were observed by SEM and analyzed by XPS. Figure 1 showed Li | Li cell test results at 0.4 mA cm−2 and 30 ℃ in different electrolytic solutions. Fig ure 1a for that in 1.0 M LiTFSI/G4 showed gradual decrease in overvoltages and unstable polarization curves. These two features suggested that the Li electrode protection by the Li2O layer from O2 gas could not withstand the current density and the exposed Li metal reacted with the solvent and electrolyte, resulting in growing Li dendrite deposition. On the other hand, Figure 1B for that in the 1.0 M LiNO3 / G4 overvoltages, suggesting suppressed Li-electrolytic solution showed very flat polarization plateaus and slightly growing dendrite formation. The difference between Figure 1a and 1b demonstrated the effect of Li2O protective layer of Li surface formed by the reaction between Li and NO3 −. Figure 2 showed the SEM image of the Li electrode after the dissolution/deposition test for 15 cycles and the surface analysis by C1s XPS. Figure 2a for LiTFSI/G4 electrolytic solution showed bulky surface layer as thick as 30 µm accompanied by a large dent. Figure 2b suggested various kind of C-containing deposits on the Li surface, which was presumably decomposed products of electrolytic solution. Therefore, Figure 2a and 2b were well consistent with Figure 1a which suggested successive surface reactions. Figure 2c and 2d for LiNO3/G4 electrolytic solution, on the contrary, showed thin surface layer and poor amount of surface products, even though the current density, 0.6 mA cm−2, was higher than that in Figure 2a, 0.4 mA cm−2. These results suggested steady surface protected by Li2O layer and were also consistent with Figure 1b. Other results presenting the effect of current densities and temperatures will be reported in our presentation to clarify the whole picture of Li dissolution/deposition reaction mechanism. References [1] M. Saito et al. J. Electrochem. Soc., 164, 2872–2880 (2017). [2] M. Saito et al. J. Electrochem. Soc., 168, 010520 (2021). Acknowledgement This study was supported by JST Project ALCA-SPRING (JPMLAL1301) and NIMS Joint Research Hub Program, Japan Figure 1
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Contreras Ramírez, Jesús Miguel, et Meribary Monsalve. « Synthesis and characterization of poly(1-methyltrimethylene carbonate) (PMTMC) by mean ring-opening polymerization ». Revista Bases de la Ciencia. e-ISSN 2588-0764 5, no 3 (31 décembre 2020) : 21. http://dx.doi.org/10.33936/rev_bas_de_la_ciencia.v5i3.1863.

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In this work, the activity of samarium (III) acetate (Sm(OAc)3) was evaluated as a possible initiator in the ring opening polymerization (ROP) of 1-methyltrimethylene carbonate (MTMC). The effects of temperature (Tr) and monomer-initiator molar ratio (M/I) on the molecular characteristics (conversion, dispersity, and molar mass) of the polymers obtained were analyzed. The reaction temperature was varied between 90 and 160 °C and the molar ratio M/I between 200 and 1000. The molar mass of the products was obtained by size exclusion chromatography (SEC), while its structure was analyzed using FT-IR and 1H-NMR spectroscopy. Thermal polymerization experiments (in the absence of an initiator) were performed in order to evaluate the effectiveness of the initiator. The comparison between the thermal polymerization of MTMC and its polymerization in the presence of Sm(OAc)3, suggests that acetate has very low catalytic activity as the initiator of the ROP of PMTMC. The molar masses of the polymers obtained ranged between 6000 and 10000 Dalton, and the monomer to polymer conversions varied between 9 and 30 %. SEC chromatograms showed monomodal and symmetric curves, suggesting that only one type of active species participates in the polymerization process. Based on the structural analysis, a polymerization mechanism was proposed in which the water possibly acts as the only active species that initiates the reaction. Palabra clave: Samarium (III) acetate, ring-opening polymerization, 1-methyltrimethylenecarbonate, poly(1-methyltrimethylenecarbonate). Abstract En este trabajo se evaluó la actividad del acetato de samario (III) (Sm(OAc)3) como posible iniciador en la polimerización de apertura de anillo (PAA) del carbonato de 1-metiltrimetileno (MTMC). Se analizaron los efectos de la temperatura (Tr) y relación molar monómero-iniciador (M/I) sobre las características moleculares (conversión, dispersidad y masa molar) de los polímeros obtenidos. La temperatura de reacción se varió entre 90 y 160 °C y la relación molar M/I entre 200 y 1000. La masa molar de los productos se obtuvo mediante cromatografía de exclusión por tamaño, mientras que su estructura fue analizada mediante espectroscopia FT-IR y 1H-RMN. Además, se realizaron algunos experimentos de polimerización térmica (en ausencia de iniciador) que sirvieron de referencia para evaluar la efectividad del iniciador. La comparación de los resultados obtenidos en la polimerización térmica y en presencia del Sm(OAc)3 indicó que este último presenta muy poca actividad catalítica como iniciador de la PAA de PMTMC. Las masas molares de los polímeros obtenidos oscilaron entre 6000 y 10000 Dalton, mientras que las conversiones de monómero a polímero variaron entre 9 y 30%. Los cromatogramas SEC mostraron curvas mono-modales y simétricas, indicando que en el proceso de polimerización participa un solo tipo de especie activa. En base al análisis estructural, mediante técnicas espectroscópicas, se propuso un mecanismo de reacción para la polimerización en la que el agua posiblemente actúa como la única especie activa iniciadora de la reacción. Keywords: Acetato de samario (III), polimerización por apertura de anillo, 1-metiltrimetilencarbonato, poli(1-metiltrimetilencarbonato).
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44

Olędzki, Juliusz. « On symmetric products ». Fundamenta Mathematicae 131, no 3 (1988) : 185–90. http://dx.doi.org/10.4064/fm-131-3-185-190.

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Mukai, Shigeru. « Curves and Symmetric Spaces, I ». American Journal of Mathematics 117, no 6 (décembre 1995) : 1627. http://dx.doi.org/10.2307/2375032.

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Mukai, Shigeru. « Curves and symmetric spaces, II ». Annals of Mathematics 172, no 3 (5 octobre 2010) : 1539–58. http://dx.doi.org/10.4007/annals.2010.172.1539.

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47

Şahin, Mesut, et Nil Şahin. « On pseudo symmetric monomial curves ». Communications in Algebra 46, no 6 (15 décembre 2017) : 2561–73. http://dx.doi.org/10.1080/00927872.2017.1392532.

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48

Farnsworth, David L. « Axes for symmetric convex curves ». Mathematical Gazette 102, no 553 (8 février 2018) : 23–30. http://dx.doi.org/10.1017/mag.2018.4.

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Curves are given in polar coordinates (r, θ)by equations of the form r = f (θ), where for f (θ) > 0 all θ. Consider curves which are symmetric about the origin O, so that, f(θ + π) = f (θ) for all θ. For such a curve, its interior is the set {(r, θ) : 0 ≤ r ≤ f (θ)}. Further, assume that the curve is convex. Recall that a closed curve is convex if a line segment between any two of its points has no points exterior to the curve [1], [2, pp. 198-203]. We call these curves M-curves, because the curves are fundamental objects in Minkowski geometry, where they are called Minkowski circles or simply circles [3, 4]. That application is briefly discussed in the Section 4 but is not required for our purposes.Examples of M-curves are displayed in Figures 1 to 6. In order to express these curves as functions in rectangular coordinates, we need axes.
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Seidel, Hans-Peter. « Symmetric triangular algorithms for curves ». Computer Aided Geometric Design 7, no 1-4 (juin 1990) : 57–67. http://dx.doi.org/10.1016/0167-8396(90)90021-i.

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Gaskell, P. H., F. Gürcan, M. D. Savage et H. M. Thompson. « Stokes flow in a double-lid-driven cavity with free surface side walls ». Proceedings of the Institution of Mechanical Engineers, Part C : Journal of Mechanical Engineering Science 212, no 5 (1 mai 1998) : 387–403. http://dx.doi.org/10.1243/0954406981521312.

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Stokes flow is considered in a rectangular double-lid-driven cavity with free surface side walls, aspect ratio A and speed ratio S= U1/ U2, where U1 and U2 are lid velocities, as an idealized model for two-dimensional viscous flow in the ‘bead’ of a two-roll, meniscus coating system. For S ≤ 0 (> 0) there is one (two) large eddy (eddies) within the cavity with one (two) stagnation points on the centre-line between the free surfaces. Various transformations of flow structure arising as a result of flow bifurcations at these stagnation points are identified as the two control parameters A and S are continuously varied. In the case of symmetric flow, S= -1, reducing A from A = 2.5 produces a sequence of pitchfork bifurcations at which a stagnation-saddle point changes to a centre (or vice versa) with the generation of two additional stagnation points. As A → 0 and the number of stagnation points increases, it is shown that the flow structure consists of a series of nested separatrices, each contained within the central section of the previous one. In the case of asymmetric flow, S ≠ -1, S < 0, the above pattern of behaviour is repeated as A is reduced from A = 2.5, apart from an initial saddle-node bifurcation at which a saddle and a centre annihilate each other. When the lids move in the same direction ( S > 0) bifurcations may arise separately or simultaneously in each of the two large eddies. Again as A → 0 with S constant, nested separatrices appear in both eddies. The key results are displayed via bifurcation curves in an ( S, A) control space diagram.
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