6,413 research outputs found

    RPNet: an End-to-End Network for Relative Camera Pose Estimation

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    This paper addresses the task of relative camera pose estimation from raw image pixels, by means of deep neural networks. The proposed RPNet network takes pairs of images as input and directly infers the relative poses, without the need of camera intrinsic/extrinsic. While state-of-the-art systems based on SIFT + RANSAC, are able to recover the translation vector only up to scale, RPNet is trained to produce the full translation vector, in an end-to-end way. Experimental results on the Cambridge Landmark dataset show very promising results regarding the recovery of the full translation vector. They also show that RPNet produces more accurate and more stable results than traditional approaches, especially for hard images (repetitive textures, textureless images, etc). To the best of our knowledge, RPNet is the first attempt to recover full translation vectors in relative pose estimation

    Product recognition in store shelves as a sub-graph isomorphism problem

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    The arrangement of products in store shelves is carefully planned to maximize sales and keep customers happy. However, verifying compliance of real shelves to the ideal layout is a costly task routinely performed by the store personnel. In this paper, we propose a computer vision pipeline to recognize products on shelves and verify compliance to the planned layout. We deploy local invariant features together with a novel formulation of the product recognition problem as a sub-graph isomorphism between the items appearing in the given image and the ideal layout. This allows for auto-localizing the given image within the aisle or store and improving recognition dramatically.Comment: Slightly extended version of the paper accepted at ICIAP 2017. More information @project_page --> http://vision.disi.unibo.it/index.php?option=com_content&view=article&id=111&catid=7

    CVaR minimization by the SRA algorithm

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    Using the risk measure CV aR in �nancial analysis has become more and more popular recently. In this paper we apply CV aR for portfolio optimization. The problem is formulated as a two-stage stochastic programming model, and the SRA algorithm, a recently developed heuristic algorithm, is applied for minimizing CV aR

    Ellipsometric measurements of the refractive indices of linear alkylbenzene and EJ-301 scintillators from 210 to 1000 nm

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    We report on ellipsometric measurements of the refractive indices of LAB-PPO, Nd-doped LAB-PPO and EJ-301 scintillators to the nearest +/-0.005, in the wavelength range 210-1000 nm.Comment: 7 pages, 4 figure

    Numerical modelling of drawbeads for forming of aluminium alloys

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    The drawbeads in stamping tools are usually designed based on experience from the forming of steel. However, aluminium alloys display different forming behaviour to steels, which is not reflected in the drawbead design for tools used for stamping aluminium. This paper presents experimental results from different semi-circular drawbead geometries commonly encountered in automotive dies and compares them to those obtained from Stoughton's analytical drawbead model and the 2D plane strain drawbead model set up using LS-DYNA. The study was conducted on lubricated NG5754 strips. The results presented are in terms of drawbead restraining force versus strip displacement, as a function of drawbead depth. The FE drawbead model agrees well with the experiments whereas the analytical model overpredicted the drawbead forces

    Oral salmon calcitonin reduces cartilage and bone pathology in an osteoarthritis rat model with increased subchondral bone turnover

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    SummaryObjectivesTraumatic osteoarthritis (OA) is possibly augmented by effects from loss of sex hormones. Salmon calcitonin is shown to reduce OA pathogenesis and bone resorption. We investigated the effects of oral salmon calcitonin treatment and ovariectomy on cartilage and bone pathology in a traumatic OA model.MethodsSix groups with 10 7-month-old female Sprague Dawley rats each were subjected to bilateral meniscectomy (MNX), ovariectomy (OVX) or Sham surgery and treated for 8 weeks with oral salmon calcitonin (CT) or vehicle (V) in the following way: (1) Sham+V; (2) MNX+V; (3) MNX+CT; (4) OVX+V; (5) MNX/OVX+V; (6) MNX/OVX+CT. Weights were recorded weekly and CTX-II was measured in serum. At termination 56 days post-surgery, the right tibia was analyzed for changes in articular cartilage thickness, extent of cartilage damage and subchondral bone changes in predefined zones, as recommended in the novel OARSI histopathology score.ResultsThe combined MNX/OVX model produced a significantly reduced cartilage thickness (P=0.033) in the outer zone (Z1) of the tibial plateau and increased calcified cartilage damage (P=0.0004) and serum CTX-II (P=0.003). Addition of OVX to MNX significantly increased the width of matrix damage at the surface (P=0.025) and 50% cartilage depth (P=0.004). Treatment with oral salmon calcitonin counteracted the loss of cartilage thickness (P=0.055), significantly reduced subchondral bone damage score (P=0.019) and reduced the type II collagen degradation (P=0.009).ConclusionsAddition of ovariectomy augmented site-specific traumatic OA pathology, which was reduced by oral salmon calcitonin treatment. Treatments for OA might ideally affect both bone and cartilage

    An analysis of lexical collocation errors in students’ writing

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    Mastering lexical collocation uses in learning English as a foreign language is absolutely essential to develop students’ communicative skills and linguistic abilities. Most students, however, have problems with putting words together in a characteristic of “natural” English native speaker-like manner during writing. Students tend to use strange lexical collocation expressions therefore students’ language production does not sound natural and carries imprecise meaning. With regard to this underlying issue, the main emphasis of the current study was lying on the investigation of the types and the causes of lexical collocation error committed by EFL students in their argumentative writing. Through a qualitative research approach applying a descriptive-analytic method, sixteen university students were chosen purposively. The data were collected from two principal sources i.e., students’ writing samples and semi-structured interviews. In terms of data analysis technique, this study employed an error analysis technique developed by Ellis (1994) to analyze the obtained lexical collocation errors and applied a content analysis technique provided by Kumar (2011) to analyze the interview results. The study revealed 54 erroneousness of lexical collocation production consisting of verb + noun/pronoun (PP), adjective + noun, adverb + adjective, noun + noun, and verb + adverb combination. These errors were caused by a lack of collocation competence, native language influence, the use of synonym, overgeneralization, and approximation

    Evaluation of the teaching and learning in listening subject

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    This present study is conducted to evaluate the teaching of listening skills in the English Department at Gorontalo State University. Evaluation in this study is to benchmark the current practice of teaching listening in the English Department of State University of Gorontaloto the research-based practice. Research finding suggests that the teaching of listening to the English Department students partly has followed methodologies proposed by Richards and Goh (2008). This study shows that in general the practice of the teaching of listening at the English Department of State University of Gorontalo is based on research-based methodologies. However, there are some points that need to be improved. Since the result of the study has addressed only some of the issues in the teaching of listening, therefore, future research on other issues of listening teaching needs to be done

    Scaling in Plasticity-Induced Cell-Boundary Microstructure: Fragmentation and Rotational Diffusion

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    We develop a simple computational model for cell boundary evolution in plastic deformation. We study the cell boundary size distribution and cell boundary misorientation distribution that experimentally have been found to have scaling forms that are largely material independent. The cell division acts as a source term in the misorientation distribution which significantly alters the scaling form, giving it a linear slope at small misorientation angles as observed in the experiments. We compare the results of our simulation to two closely related exactly solvable models which exhibit scaling behavior at late times: (i) fragmentation theory and (ii) a random walk in rotation space with a source term. We find that the scaling exponents in our simulation agree with those of the theories, and that the scaling collapses obey the same equations, but that the shape of the scaling functions depend upon the methods used to measure sizes and to weight averages and histograms
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