995 research outputs found

    GPS/INS Integration Accuracy Enhancement Using the Interacting Multiple Model Nonlinear Filters

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    In this paper, performance evaluation for various single model nonlinear filters and nonlinear filters with interactingmultiple model (IMM) framework is carried out. A high gain (high bandwidth) filter is needed to response fast enoughto the platform maneuvers while a low gain filter is necessary to reduce the estimation errors during the uniformmotion periods. Based on a soft-switching framework, the IMM algorithm allows the possibility of using highly dynamicmodels just when required, diminishing unrealistic noise considerations in non-maneuvering situations. The IMMestimator obtains its estimate as a weighted sum of the individual estimates from a number of parallel filters matchedto different motion modes of the platform. The use of an IMM allows exploiting the benefits of high dynamic models inthe problem of vehicle navigation. Simulation and experimental results presented in this paper confirm theeffectiveness of the method

    Numerical Simulation of Laminar and Turbulent Methane/Air Flames Based on a DRG-Derived Skeletal Mechanism

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    Minimal model of associative learning for cross-situational lexicon acquisition

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    An explanation for the acquisition of word-object mappings is the associative learning in a cross-situational scenario. Here we present analytical results of the performance of a simple associative learning algorithm for acquiring a one-to-one mapping between NN objects and NN words based solely on the co-occurrence between objects and words. In particular, a learning trial in our learning scenario consists of the presentation of C+1<NC + 1 < N objects together with a target word, which refers to one of the objects in the context. We find that the learning times are distributed exponentially and the learning rates are given by ln[N(N1)C+(N1)2]\ln{[\frac{N(N-1)}{C + (N-1)^{2}}]} in the case the NN target words are sampled randomly and by 1Nln[N1C]\frac{1}{N} \ln [\frac{N-1}{C}] in the case they follow a deterministic presentation sequence. This learning performance is much superior to those exhibited by humans and more realistic learning algorithms in cross-situational experiments. We show that introduction of discrimination limitations using Weber's law and forgetting reduce the performance of the associative algorithm to the human level

    Fabrication of extracellular matrix-derived foams and microcarriers as tissue-specific cell culture and delivery platforms

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    © 2017 Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Cell function is mediated by interactions with the extracellular matrix (ECM), which has complex tissue-specific composition and architecture. The focus of this article is on the methods for fabricating ECM-derived porous foams and microcarriers for use as biologically-relevant substrates in advanced 3D in vitro cell culture models or as pro-regenerative scaffolds and cell delivery systems for tissue engineering and regenerative medicine. Using decellularized tissues or purified insoluble collagen as a starting material, the techniques can be applied to synthesize a broad array of tissue-specific bioscaffolds with customizable geometries. The approach involves mechanical processing and mild enzymatic digestion to yield an ECM suspension that is used to fabricate the three-dimensional foams or microcarriers through controlled freezing and lyophilization procedures. These pure ECM-derived scaffolds are highly porous, yet stable without the need for chemical crosslinking agents or other additives that may negatively impact cell function. The scaffold properties can be tuned to some extent by varying factors such as the ECM suspension concentration, mechanical processing methods, or synthesis conditions. In general, the scaffolds are robust and easy to handle, and can be processed as tissues for most standard biological assays, providing a versatile and user-friendly 3D cell culture platform that mimics the native ECM composition. Overall, these straightforward methods for fabricating customized ECM-derived foams and microcarriers may be of interest to both biologists and biomedical engineers as tissue-specific cell-instructive platforms for in vitro and in vivo applications

    Genomic and biologic comparisons of cyprinid herpesvirus 3 strains

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    Cyprinid herpesvirus 3 (CyHV-3) is the archetypal fish alloherpesvirus and the etiologic agent of a lethal disease in common and koi carp. To date, the genome sequences of only four CyHV-3 isolates have been published, but no comparisons of the biologic properties of these strains have been reported. We have sequenced the genomes of a further seven strains from various geographical sources, and have compared their growth in vitro and virulence in vivo. The major findings were: (i) the existence of the two genetic lineages previously described as European and Asian was confirmed, but inconsistencies between the geographic origin and genotype of some strains were revealed; (ii) potential inter-lineage recombination was detected in one strain, which also suggested the existence of a third, as yet unidentified lineage; (iii) analysis of genetic disruptions led to the identification of non-essential genes and their potential role in virulence; (iv) comparison of the in vitro and in vivo properties of strains belonging to the two lineages revealed that inter-lineage polymorphisms do not contribute to the differences in viral fitness observed; and (v) a negative correlation was observed among strains between viral growth in vitro and virulence in vivo. This study illustrates the importance of coupling genomic and biologic comparisons of viral strains in order to enhance understanding of viral evolution and pathogenesis

    Entanglement in quantum computers described by the XXZ model with defects

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    We investigate how to generate maximally entangled states in systems characterized by the Hamiltonian of the XXZ model with defects. Some proposed quantum computers are described by such model. We show how the defects can be used to obtain EPR states and W states when one or two excitations are considered.Comment: 4 pages, 1 figur

    Diffusion-limited reaction for the one-dimensional trap system

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    We have previously discussed the one-dimensional multitrap system of finite range and found the somewhat unexpected result that the larger is the number of imperfect traps the higher is the transmission through them. We discuss in this work the effect of a small number of such traps arrayed along either a constant or a variable finite spatial section. It is shown that under specific conditions, to be described in the following, the remarked high transmission may be obtained for this case also. Thus, compared to the theoretical large number of traps case these results may be experimentally applied to real phenomenaComment: 18 pages, 8 PS Figures; 3 former figures were removed, a new section added and the representation is improve

    Repulsion-Sustained Supercurrent and Flux Quantization in Rings of Symmetric Hubbard Clusters

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    We test the response to a threading magnetic field of rings of 5-site C4vC_{4v}-symmetric repulsive Hubbard clusters connected by weak intercell links; each 5-site unit has the topology of a CuO4_{4} cluster and a repulsive interaction is included on every site. In a numerical study of the three-unit ring with 8 particles, we take advantage of a novel exact-diagonalization technique which can be generally applied to many-fermion problems. For O-O hopping we find Superconducting Flux Quantization (SFQ), but for purely Cu-Cu links bound pair propagation is hindered by symmetry. The results agree with W=0 pairing theory.Comment: 4 pages, 2 figure

    Numerical renormalization group study of the 1D t-J model

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    The one-dimensional (1D) tJt-J model is investigated using the density matrix renormalization group (DMRG) method. We report for the first time a generalization of the DMRG method to the case of arbitrary band filling and prove a theorem with respect to the reduced density matrix that accelerates the numerical computation. Lastly, using the extended DMRG method, we present the ground state electron momentum distribution, spin and charge correlation functions. The 3kF3k_F anomaly of the momentum distribution function first discussed by Ogata and Shiba is shown to disappear as JJ increases. We also argue that there exists a density-independent JcJ_c beyond which the system becomes an electron solid.Comment: Wrong set of figures were put in the orginal submissio

    Experimental study of high strength concrete-filled circular tubular columns under eccentric loading

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    The paper describes 37 tests conducted on slender circular tubular columns filled with normal and high strength concrete subjected to eccentric axial load. The test parameters were the nominal strength of concrete (30, 70 and 90 MPa), the diameter to thickness ratio Dt, the eccentricity ratio eD and the column slenderness (LD). The experimental ultimate load of each test was compared with the design loads from Eurocode 4, which limits the strength of concrete up to 50 MPa. The aim of the paper is to establish the advisability of the use of high strength concretes as opposed to that of normal strength concretes by comparing three performance indices: concrete contribution ratio, strength index and ductility index. The results show for the limited cases analyzed that the use of high strength concrete for slender composite columns is interesting since this achieves ductile behavior despite the increase in load-carrying capacity is not greatly enhanced. © 2010 Elsevier Ltd. All rights reserved.The authors wish to express their sincere gratitude to the Spanish Ministry of Education for help provided through project BIA2005_255 and BIA 2009_09411, to the European Community for FEDER funds, and to the Fundacio Caixa Castello-Bancaixa.Portoles, J.; Romero, ML.; Bonet Senach, JL.; Filippou, F. (2011). Experimental study of high strength concrete-filled circular tubular columns under eccentric loading. Journal of Constructional Steel Research. 67(4):623-633. https://doi.org/10.1016/j.jcsr.2010.11.017S62363367
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