267 research outputs found

    Re-mining association mining results through visualization, data envelopment analysis, and decision trees

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    Re-mining is a general framework which suggests the execution of additional data mining steps based on the results of an original data mining process. This study investigates the multi-faceted re-mining of association mining results, develops and presents a practical methodology, and shows the applicability of the developed methodology through real world data. The methodology suggests re-mining using data visualization, data envelopment analysis, and decision trees. Six hypotheses, regarding how re-mining can be carried out on association mining results, are answered in the case study through empirical analysis

    Encapsulating and representing the knowledge on the evaluation of an engineering system

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    This paper proposes a cross-disciplinary methodology for a fundamental question in product development: How can the innovation patterns during the evolution of an engineering system (ES) be encapsulated, so that it can later be mined through data mining analysis methods? Reverse engineering answers the question of which components a developed engineering system consists of, and how the components interact to make the working product. TRIZ answers the question of which problem-solving principles can be, or have been employed in developing that system, in comparison to its earlier versions, or with respect to similar systems. While these two methodologies have been very popular, to the best of our knowledge, there does not yet exist a methodology that reverseengineers and encapsulates and represents the information regarding the complete product development process in abstract terms. This paper suggests such a methodology, that consists of mathematical formalism, graph visualization, and database representation. The proposed approach is demonstrated by analyzing the design and development process for a prototype wrist-rehabilitation robot

    Simulation of electricity generation by marine current turbines at Istanbul Bosphorus Strait

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    In this work, several simulations and analyses are carried out to investigate the feasibility of generating electricity from underwater sea currents at Istanbul Bosphorus Strait. Bosphorus is a natural canal which forms a border between Europe and Asia by connecting Black Sea and Marmara Sea. The differences in elevation and salinity ratios between these two seas cause strong marine currents. Depending on the morphology of the canal the speed of the flow varies and at some specific locations the energy intensity reaches to sufficient levels where electricity generation by marine current turbines becomes economically feasible. In this study, several simulations are performed for a 10 MW marine turbine farm/cluster whose location is selected by taking into account several factors such as the canal morphology, current speed and passage of vessels. 360 different simulations are performed for 15 different virtual sea states. Similarly, 8 different configurations are analyzed in order to find the optimum spacing between the turbines. Considering the spatial variations in the current speed within the selected region, the analyses are performed for three different flow speeds corresponding to +/- 10% change in the average value. For each simulation the annual energy yield and cluster efficiency are calculated. (C) 2015 Elsevier Ltd. All rights reserved

    Insights into the efficiencies of on-shore wind turbines: a data-centric analysis

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    Literature on renewable energy alternative of wind turbines does not include a multidimensional benchmarking studythat can help investment decisions as well as design processes. This paper presents a data-centric analysis of commercial on-shore wind turbines and provides actionable insights through analytical benchmarking through Data Envelopment Analysis (DEA), visual data analysis, and statistical hypothesis testing. The paper also introduces a novel visualization approach for the understanding and the interpretation of reference sets, the set of efficient wind turbines that should be taken as benchmark by inefficient ones

    Two-sided Adverse Selection and Bilateral Reviews in the Sharing Economy

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    Online peer-to-peer platforms match service providers with consumers. Both providers and consumers derive heterogeneous payoffs depending on whom they are matched with. To ensure that providers and consumers identify the most valuable matches, many of these platforms elicit relevant information from and also disclose the information to the market participants by adopting bilateral review schemes. Although the bilateral review scheme has its own merits in reducing information asymmetry and possibly enabling better matches, its impact on the various stakeholders in online peer-to-peer platforms remains unexplored. We show that, in equilibrium, the bilateral review scheme intensifies price competition among service providers to attract low-cost consumers and consequently reduces the platform\u27s profit. Interestingly, service providers may be better off with more intense price competition and lower prices when the proportion of low-cost consumers is sufficiently high. More importantly, we find that social welfare is not always higher under the bilateral review scheme compared to either the unilateral review scheme or no reviews. Our findings demonstrate that even though the bilateral review scheme eliminates the information asymmetry and adverse selection on both sides of the market, it does not necessarily enhance market efficiency when competing providers strategically respond to reviews by adjusting their prices

    Higher order splitting approaches in analysis of the Burgers equation

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    This article proposes some higher order splitting-up techniques based on cubic B-spline Galerkin finite element method in analysing the Burgers equation model. The strong form of both conservation and diffusion parts of the time-splitted Burgers equation have been considered in building the Galerkin approach. To integrate the corresponding ODE system, the Crank-Nicolson time discretization scheme is used. The proposed schemes are shown to be unconditionally stable. Two challenging examples have been considered with changing values of the kinematic viscosity constant of the medium. Especially, the cases of shock waves of severe gradient are solved and checked with both exact solution and the literature. The qualitative and quantitative results demonstrate that our numerical approach has far higher accuracy than the rival methods

    Unilateral Multiple Evanescent White Dot Syndrome-Like Reaction Following the CyberKnife Stereotactic Radiotherapy for Choroidal Malignant Melanoma

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    A 58-year-old otherwise healthy man received a diagnosis of choroidal malignant melanoma (CMM) in June 2021 and underwent a single session of (21 Gy) CyberKnife stereotactic radiotherapy (SRT). Eleven months later, we noticed 3+ anterior chamber cells with occasional vitreous cells in the left eye. Though the tumor looked regressed, there were mild optic disc leakage, early hypofluorescent and late hyperfluorescent punctate lesions scattered 360 degrees, and late staining of the mass on fluorescein angiogram. The findings were compatible with a unilateral multiple evanescent white dot syndrome (MEWDS)-like reaction that was most likely related to CyberKnife SRT-induced tumor necrosis, and a dexamethasone implant was administered intravitreally into the left eye together with topical steroids. A second intravitreal injection of dexamethasone was given three months later due to remittance of the angiographic features. As there are only a few reports on CyberKnife SRT for the treatment of CMM, we wanted to share our interesting observation of a post-treatment MEWDS-like reaction likely related to tumor necrosis syndrome with the ophthalmic community

    Laparoscopic Nephrectomy in Patients Undergoing Hemodialysis Treatment

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    With an experienced laparoscopic team of surgeons, laparoscopic nephrectomy may be performed safely
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