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952. A numerical investigation of the modified Sherman systems
- Creator:
- Nikolov, Svetoslav, Nedev, Valentin, and Zlatanov, Vassil
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chaotic dynamics, Sherman system, bifurcation, and maximal Lyapunov exponent
- Language:
- English
- Description:
- The aim of this paper was to demonstrate that it is possible to control the chaos into the Sherman system by linear feedback of own signals. After introducing of the parameter ‘α‘ in the z-equation (α → α + α1 x(t) + α2 y(t) + α3 z(t), we study how the global dynamics can be altered in a desired direction (αn are considered as free parameters). We make a detailed bifurcation investigation of the modified Sherman systems by varying the parameters αn. Finally, we calculate the maximal Lyapunov exponent, where the chaotic motion of modified Sherman system exists. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
953. A numerical study of effects of the manufacture perturbations to contacts of the total hip replacement
- Creator:
- Koukal, Milan, Fuis, Vladimír, Florian, Zdeněk, and Janíček, Přemysl
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- total hip replacement, FEM, roundness, contact pressure, frictional moment, and biomechanics
- Language:
- English
- Description:
- In endoprosthesis surgery there are typically a high percentage of implant defects, these can lead to failure of the whole prosthesis. One type of total hip replacement function loss is acetabular cup loosening from the pelvic bone. This article examines manufacture perturbations as one of the possible reasons for this kind of failure. Both dimension and geometry manufacturing perturbations of ceramic head and polyethylen cup were analyzed. We find that perturbations in the variables analysed here affect considered values of contact pressure and frictional moment. Furthermore, contact pressure and frictonal moment are quantities affecting replacement success and durability. From obtained results we can recommend to fit head and cup with a clearance of between 0 mm andd 0.05 mm. We do not recommend using interference type of fit. Roundness perturbation of ceramic head should not exceed 0.025 mm. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
954. A numerical study of Newton interpolation with extremely high degrees
- Creator:
- Breuss, Michael, Kemm, Friedemann, and Vogel, Oliver
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- polynomial interpolation, Newton interpolation, interpolation nodes, Chebyshev nodes, Leja ordering, and fast Leja points
- Language:
- English
- Description:
- In current textbooks the use of Chebyshev nodes with Newton interpolation is advocated as the most efficient numerical interpolation method in terms of approximation accuracy and computational effort. However, we show numerically that the approximation quality obtained by Newton interpolation with Fast Leja (FL) points is competitive to the use of Chebyshev nodes, even for extremely high degree interpolation. This is an experimental account of the analytic result that the limit distribution of FL points and Chebyshev nodes is the same when letting the number of points go to infinity. Since the FL construction is easy to perform and allows to add interpolation nodes on the fly in contrast to the use of Chebyshev nodes, our study suggests that Newton interpolation with FL points is currently the most efficient numerical technique for polynomial interpolation. Moreover, we give numerical evidence that any reasonable function can be approximated up to machine accuracy by Newton interpolation with FL points if desired, which shows the potential of this method.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
955. A numerical study of pressure changes in dead-end pores
- Creator:
- Fathaddin, Muhammad Taufiq, Awang, Mariyamni B., and Ardjani, Karnata
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- dead-end pore, porous media, source, sink, mŕtve póry, pórovité prostredie, zdroj, and odber
- Language:
- Slovak
- Description:
- Dead-end pores are usually present in natural porous media especially in consolidated sandstone and limestone rocks. However, the presence of the dead-end pores is usually ignored. Then, the influences of the dead end pores to the flow system are also neglected. In this paper, pressure changes for the periods of transient and steady state of the dead-end pores are studied using lattice gas automata model. A simulation result is compared with the past works. They show that the model is viable to perform simulation of deadend pore pressure. Some parameters such as pressure distribution and size of neck and body of the dead-end pores are varied to examine their effects. We found that the parameters affect the rate of pressure change during transient period. In addition, the parameters also affect the pressure fluctuation during steady state period. The dead-end pores have function either as source or sink in the transient period depend on initial and injection pressures. During steady state period, the dead-end pores behave both as source and sink since the pressure in the pores fluctuates around an equilibrium pressure between the pressure of dead-end pore and that of main channel at the neck position of dead-end pore. and Takzvané mŕtve póry (neprietočné póry) sa často nachádzajú v prírodných pórovitých prostrediach, predovšetkým v skonsolidovaných pieskovcoch a vo vápencoch. Obvykle sa ich existencii nevenuje pozornosť. Pozornosť sa nevenuje ani ich vplyvu na prúdenie v tomto systéme. V tomto príspevku sú študované zmeny tlaku v mŕtvych póroch počas neustáleného a ustáleného prúdenia s použitím ''lattice gas automata'' modelu. Výsledky simulácie sme porovnali s predchádzajúcimi prácami. Výsledky naznačujú, že tento model je vhodný na simuláciu zmien tlakov v mŕtvych póroch. Vplyv niektorých parametrov, ako je rozdelenie tlakov a tvary ''krčkov'' (spojovacích pórov) ako aj mŕtvych pórov boli menené tak, aby sme mohli pozorovať ich vplyv na prúdenie. Zistili sme, že tieto parametre ovplyvňujú rýchlosť zmien tlakov počas neustáleného prúdenia. Navyše sme zistili, že tieto parametre ovplyvňujú fluktuáciu tlakov počas ustáleného prúdenia. Mŕtve póry môžu počas neustáleného prúdenia fungovať ako zdroje alebo odbery, v závislosti od počiatočného, alebo ''plniaceho'' tlaku. Počas ústáleného prúdenia sa mŕtve póry správajú ako zdroje alebo aj odbery, pretože tlak v póroch fluktuuje okolo rovnovážneho tlaku medzi tlakom v mŕtvych póroch a hlavným kanálom v závislosti od vlastností ''krčku'' mŕtveho póru.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
956. A numerical study of resonances in collisional disks: application to planetary ring area
- Creator:
- Sicardy, Bruno
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- space research, planetary rings, and collisions
- Language:
- Czech
- Description:
- Many recent observations have shown that resonances have a wide variety of effects in planetary rings: spiral waves, gaps, confinement, sharp edges, arcs. While resonances are known to be associated with such structures, the role of inter-particle collisions is still poorly understood, although necessary to explain the long term evolution of the rings. In an effort to better understand the associated dynamics, we have performed numerical simulations of colliding particles orbiting a massive central planet. The code simulates the 3-D motion of 100 identical spherical particles orbiting a massive cental body and suffering inelastic collisions while being perturbed by one or more satellites. We used this code to explore in more details the dynamics of are rings, and to explain in particular the reeent observations of are structures around Neptune. Clusters of particles at a satellite’s Lagrangian point {L4 or L5) are shown to be dispersed by dissipative effects. However, a second satellite can stabilize the system by providing sufficient energy through a Lindblaďs resonance m±l:m. Other dynamically equivalent configurations (e.g. only one satellite, but with an eccentric orbit) can also stabilize are sytems, in accord with current analytical models. We examine the roles of collisions at Lindblad and corotation resonances in various cases. Arcs remain at the potential maxima created by the corotations. However, stability requires that the satellites’ masses be within a limited range: small satellites cannot provide enough energy while large ones give too much, so the arc can disperse.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
957. A one-way ANOVA test for functional data with graphical interpretation
- Creator:
- Mrkvička, Tomáš, Myllymäki, Mari, Jílek, Milan, and Hahn, Ute
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- global envelope test, groups comparison, permutation test, Europe, fiscal decentralization, and nonparametrical methods
- Language:
- English
- Description:
- A new functional ANOVA test, with a graphical interpretation of the result, is presented. The test is an extension of the global envelope test introduced by Myllymäki et al. (2017, Global envelope tests for spatial processes, J. R. Statist. Soc. B 79, 381-404, doi: 10.1111/rssb.12172). The graphical interpretation is realized by a global envelope which is drawn jointly for all samples of functions. If a mean function computed from the empirical data is out of the given envelope, the null hypothesis is rejected with the predetermined significance level α. The advantages of the proposed one-way functional ANOVA are that it identifies the domains of the functions which are responsible for the potential rejection. We introduce two versions of this test: the first gives a graphical interpretation of the test results in the original space of the functions and the second immediately offers a post-hoc test by identifying the significant pair-wise differences between groups. The proposed tests rely on discretization of the functions, therefore the tests are also applicable in the multidimensional ANOVA problem. In the empirical part of the article, we demonstrate the use of the method by analyzing fiscal decentralization in European countries.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
958. A particle swarm optimization-threshold accepting hybrid algorithm for unconstrained optimization
- Creator:
- Maheshkumar , Y., Ravi, V., and Abraham , Ajith
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Particle swatmk optimization, threshold accepting algorithm, hybrid metaheuristics, and unconstrained optimization
- Language:
- English
- Description:
- In this paper, we propose a novel hybrid metaheuristic algorithm, which integrates a Threshold Accepting algorithm (TA) with a traditional Particle Swarm Optimization (PSO) algorithm. We used the TA as a catalyst in speeding up convergence of PSO towards the optimal solution. In this hybrid, at the end of every iteration of PSO, the TA is invoked probabilistically to refine the worst particle that lags in the race of finding the solution for that iteration. Consequently the worst particle will be refined in the next iteration. The robustness of the proposed approach has been tested on 34 unconstrained optimization problems taken from the literature. The proposed hybrid demonstrates superior preference in terms of functional evaluations and success rate for 30 simulations conducted.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
959. A parvicapsulid (Myxozoa) infecting Sprattus sprattus and Clupea harengus (Clupeidae) in the Northeast Atlantic uses Hydroides norvegicus (Serpulidae) as invertebrate host
- Creator:
- Køie, Marianne, Karlsbakk, Egil, Bårdsgjære Einen, Ann-Cathrine, and Nylund, Are
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Myxozoa, Parvicapsulidae, Clupea harengus, Sprattus sprattus, actinospores, life cycle, Denmark, and Norway
- Language:
- English
- Description:
- A myxosporean producing actinospores of the tetractinomyxon type in Hydroides norvegicus Gunnerus (Serpulidae) in Denmark was identified as a member of the family Parvicapsulidae based on small-subunit ribosomal DNA (SSU rDNA) sequences. Myxosporean samples from various Danish and Norwegian marine fishes were examined with primers that detect the novel myxosporean. Sprattus sprattus (Linnaeus) and Clupea harengus Linnaeus (Teleostei, Clupeidae) were found to be infected. The sequences of this parvicapsulid from these hosts were consistently slightly different (0.8% divergence), but both these genotypes were found in H. norvegicus. Disporic trophozoites and minute spores of a novel myxosporean type were observed in the renal tubules of some of the hosts found infected through PCR. The spores appear most similar to those of species of Gadimyxa Køie, Karlsbakk et Nylund, 2007, but are much smaller. The actinospores of the tetractinomyxon type from H. norvegicus have been described previously. In GenBank, the SSU rDNA sequences of Parvicapsulidae gen. sp. show highest identity (82%) with Parvicapsula minibicornis Kent, Whitaker et Dawe, 1997 infecting salmonids (Oncorhynchus spp.) in fresh water in the western North America. A phylogenetic analysis places P. minibicornis and Parvicapsulidae gen. sp. in a sister clade to the other parvicapsulids (Parvicapsula spp. and Gadimyxa spp.).
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
960. A periodic solution of delayed celluar neural networks
- Creator:
- Zhu, Peiyong and Sun, Shixin
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Celluar neural networks, periodic solution, convergents exponentially, and Lipschitz condition
- Language:
- English
- Description:
- We mainly prove: Assume that each output function of DCNN is bounded on R and satisfies the Lipschitz condition, if is a periodic function with period ω each i, then DCNN has a unique ω-period solution and all other solutions of DCNN converge exponentially to it, where is a Lipschitz constant of for i=1,2,...,n.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public