931 research outputs found

    Disconnected Skeleton: Shape at its Absolute Scale

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    We present a new skeletal representation along with a matching framework to address the deformable shape recognition problem. The disconnectedness arises as a result of excessive regularization that we use to describe a shape at an attainably coarse scale. Our motivation is to rely on the stable properties of the shape instead of inaccurately measured secondary details. The new representation does not suffer from the common instability problems of traditional connected skeletons, and the matching process gives quite successful results on a diverse database of 2D shapes. An important difference of our approach from the conventional use of the skeleton is that we replace the local coordinate frame with a global Euclidean frame supported by additional mechanisms to handle articulations and local boundary deformations. As a result, we can produce descriptions that are sensitive to any combination of changes in scale, position, orientation and articulation, as well as invariant ones.Comment: The work excluding {\S}V and {\S}VI has first appeared in 2005 ICCV: Aslan, C., Tari, S.: An Axis-Based Representation for Recognition. In ICCV(2005) 1339- 1346.; Aslan, C., : Disconnected Skeletons for Shape Recognition. Masters thesis, Department of Computer Engineering, Middle East Technical University, May 200

    Toward the Design of Efficient Move Strategies for Local Search

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    Despite the huge number of studies in the metaheuristic field, it remains difficult to understand the relative impact of their elementary components. A major aspect determining the general efficiency of metaheuristics resides in the way to exploit a neighborhood structure to move within a search space. In particular, the study of iterative improvement neighborhood searches (climbers) provides guidelines to better understand local searches behavior. Several studies clearly state that some climbing strategies are more suited than classical best and first improvement, on which most local searches are based. Here, we are interested in determining empirically climbing strategies that allow the attainment of high quality local optima. First, we study alternative move selection criteria that globally outperform best and first improvement. Unfortunately, these strategies are time-consuming and consequently reduce their possibilities of integration into advanced metaheuristics. Then, we investigate ways to reduce their computational cost by approximation. Empirical studies on NK landscapes allow the identification of move criteria that offer good tradeoffs between the quality of the local optima attained and the computational time needed to reach them

    Sampled Walk and Binary Fitness Landscapes Exploration

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    In this paper we present and investigate partial neighborhood local searches, which only explore a sample of the neighborhood at each step of the search. We particularly focus on establishing link between the structure of optimization problems and the efficiency of such local search algorithms. In our experiments we compare partial neighborhood local searches to state-of-the-art tabu search and iterated local search and perform a parameter sensitivity analysis by observing the efficiency of partial neighborhood local searches with different size of neighborhood sample. In order to facilitate the extraction of links between instances structure and search algorithm behavior we restrain the scope to binary fitness landscapes, such as NK landscapes and landscapes derived from UBQP

    Worst Improvement based Iterated Local Search

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    To solve combinatorial optimization problems, many metaheuristics use first or best improvement hill-climbing as intensification mechanism in order to find local optima. In particular, first improvement offers a good tradeoff between computation cost and quality of reached local optima. In this paper, we investigate a worst improvement-based moving strategy, never considered in the literature. Such a strategy is able to reach good local optima despite requiring a significant additional computation cost. Here, we investigate if such a pivoting rule can be efficient when considered within metaheuristics, and especially within iterated local search (ILS). In our experiments, we compare an ILS using a first improvement pivoting rule to an ILS using an approximated version of worst improvement pivoting rule. Both methods are launched with the same number of evaluations on bit-string based fitness landscapes. Results are analyzed using some landscapes’ features in order to determine if the worst improvement principle should be considered as a moving strategy in some cases

    KESESUAIAN KAWASAN UNTUK PENGEMBANGAN EKOWISATA HUTAN MANGROVE KUALA LANGSA

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    Langsa City is mostly in the form of land and coastal areas, especially the Kuala Langsa area which has the potential to be developed into an ecotourism development area because the mangrove ecosystem is still natural and preserved. This study aims to determine the level of land suitability for the development of mangrove forest ecotourism in Kuala Langsa. Primary data in the form of mangrove density, mangrove thickness, types of mangroves, tides, and biota objects were obtained through observation at 6 observation locations using Purposive sampling and Line transect point methods, while secondary data included geographical conditions, and tidal data obtained through literature studies. Vegetation data were analyzed by calculating plant species density and tourism suitability analyzed using tourism suitability index (IKW). Mangrove species found at the study site included, Bruguiera gymnorrhiza, Ceriops tagal, Rhizophora apiculata, Rhizophora mucronata, Sonneratia caseolaris and Xylocarpus granatum. The results showed that the IKW value of 60% included in the S2 category (as appropriate). The limiting factor is the density of mangroves which only have a value of 8 with the S3 conformity category (as conditional). With the limiting factor is the density of mangroves which only have a value of 4 with the suitability category S3 (not suitable). As for suggestions that can be given to the manager of Kuala Langsa mangrove forest Ecotourism so that the existence of Ecotourism can be sustainable is the need for Pentahelix Synergy in the management of the ecotourism

    A Mammalian Homolog of Drosophila melanogaster Transcriptional Coactivator Intersex Is a Subunit of the Mammalian Mediator Complex

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    The multiprotein Mediator complex is a coactivator required for transcriptional activation of RNA polymerase II transcribed genes by DNA binding transcription factors. We previously partially purified a Med8-containing Mediator complex from rat liver nuclei (Brower, C. S., Sato, S., Tomomori-Sato, C., Kamura, T., Pause, A., Stearman, R., Klausner, R. D., Malik, S., Lane, W. S., Sorokina, I., Roeder, R. G., Conaway, J. W., and Conaway, R. C. (2002) Proc. Natl. Acad. Sci. U. S. A. 99, 10353–10358). Analysis of proteins present in the most highly enriched Mediator fractions by tandem mass spectrometry led to the identification of several new mammalian Mediator subunits, as well as several potential Mediator subunits. Here we identify one of these proteins, encoded by the previously uncharacterized AK000411 open reading frame, as a new subunit of the mammalian Mediator complex. The AK000411 protein, which we designate hIntersex (human Intersex), shares significant sequence similarity with the Drosophila melanogaster intersex protein, which has functional properties expected of a transcriptional coactivator specific for the Drosophila doublesex transactivator. In addition, we show that hIntersex assembles into a subcomplex with Mediator subunits p28b and TRFP. Taken together, our findings identify a new subunit of the mammalian Mediator and shed new light on the architecture of the mammalian Mediator complex

    Factors Influencing Nigeria’s Trade

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    This paper examined factor influencing Nigeria’s trade with the rest of the world using standard time series analysis technique on annual data spanning 1981 to 2012. Focus was on industrial and agricultural production. The stylized facts showed the increasing neglect the non-oil sector has suffered over the years. On average, oil trade dominates total trade and is about three times non-oil trade. Oil trade is also more volatile, about 2 times more volatile than non-oil trade. Also, oil balance of trade is comparatively two times more unstable. Nigeria’s export on average has been larger and more volatile than import due to the dominance of oil-export. All the variables were I(1) and cointegrated. The error correction results showed that in industrial output growth is more important in explaining balance of trade and total trade adjustments to equilibrium. This could be misleading, because the Nigerian industrial sector is dominated by activities in the petroleum (oil) sector which predominantly is an extractive industry. This implies primary product trade drives the Nigerian economy. This underscores why fluctuations in the crude oil market has had significant effect on the Nigerian economy in time past and in contemporary times. It was concluded that Nigeria’s trade pattern does not conform to the Hescher-Ohlin theory of factor endowment. Amongst others, it was recommended that the Nigerian state should come up with a consumption theory, where citizens and foreign nationals domiciled in the country are encouraged to consume more of made – in – Nigeria goods. Keywords: Factors, Nigeria, oil, non-oil, Trade JEL Classification: C22 F1

    Superconducting properties of the In-substituted topological crystalline insulator, SnTe

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    We report detailed investigations of the properties of a superconductor obtained by substituting In at the Sn site in the topological crystalline insulator (TCI), SnTe. Transport, magnetization and heat capacity measurements have been performed on crystals of Sn0.6_{0.6}In0.4_{0.4}Te, which is shown to be a bulk superconductor with TconsetT_c^{\rm{onset}} at ∼4.70(5)\sim4.70(5)~K and TczeroT_c^{\rm{zero}} at ∼3.50(5)\sim3.50(5)~K. The upper and lower critical fields are estimated to be μ0Hc2(0)=1.42(3)\mu_0H_{c2}(0)=1.42(3)~T and μ0Hc1(0)=0.90(3)\mu_0H_{c1}(0)=0.90(3)~mT respectively, while κ=56.4(8)\kappa=56.4(8) indicates this material is a strongly type II superconductor
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