1,894 research outputs found

    Time-Efficient resource allocation algorithm over HSDPA in femtocell networks

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    This paper presents a time-efficient optimal resource allocation algorithm aiming to maximize the system throughput of the single-user High Speed Downlink Packet Access (HSDPA) deployed in femtocell base station. The system throughput maximization with constrained total power is rst formulated as a constrained integer programming problem. We rst prove that a two-group bit and energy allocation provides the global optimum solution in the system without multipath. We then focus on the use of the two-group allocation method over frequency selective channels. A pre-processing method was used to systematically cluster and remove channels to stop using energies over severely degraded channels with the two-group allocation approach. This improves the system throughput whilst greatly reducing the computation complexity. The proposed twogroup approach with channel removal is suitable for femtocell base station with limited signal processing capability.Accepted versio

    Eddy genesis and transformation of Stokes flow in a double-lid-driven cavity. Part 2: deep cavities

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    This paper extends an earlier work [1] on the development of eddies in rectangular cavities driven by two moving lids. The streamfunction describing Stokes flow in such cavities is expressed as a series of Papkovich-Faddle eigenfunctions. The focus here is deep cavities, i.e. those with large height-to-width aspect ratios, where multiple eddies arise. The aspect ratio of the fully developed eddies is found computationally to be 1.38 > 0.05, which is in close agreement with that obtained from Moffatt's [2] analysis of the decay of a disturbance between infinite stationary parallel plates. Extended control space diagrams for both negative and positive lid speed ratios are presented, and show that the pattern of bifurcation curves seen previously in the single-eddy cavity is repeated at higher aspect ratios, but with a shift in the speed ratio. Several special speed ratios are also identified for which the flow in one or more eddies becomes locally symmetric, resulting in locally symmetric bifurcation curves. By superposing two semi-infinite cavities and using the constant velocity damping factor found by Moffatt, a simple model of a finite multiple-eddy cavity is constructed and used to explain both the repetition of bifurcation patterns and the local symmetries. The speed ratios producing partial symmetry in the cavity are shown to be integer powers of Moffatt's velocity damping factor

    Multi-dimensional Conversation Analysis across Online Social Networks

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    With the advance of the Internet, ordinary users have created multiple personal accounts on online social networks, and interactions among these social network users have recently been tagged with location information. In this work, we observe user interactions across two popular online social networks, Facebook and Twitter, and analyze which factors lead to retweet/like interactions for tweets/posts. In addition to the named entities, lexical errors and expressed sentiments in these data items, we also consider the impact of shared user locations on user interactions. In particular, we show that geolocations of users can greatly affect which social network post/tweet will be liked/ retweeted. We believe that the results of our analysis can help researchers to understand which social network content will have better visibility.Comment: Datasets will be anonymized and published at: http://akcora.wordpress.com/2013/12/24/pointer-for-datasets

    Blockchain: A Graph Primer

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    Bitcoin and its underlying technology Blockchain have become popular in recent years. Designed to facilitate a secure distributed platform without central authorities, Blockchain is heralded as a paradigm that will be as powerful as Big Data, Cloud Computing and Machine learning. Blockchain incorporates novel ideas from various fields such as public key encryption and distributed systems. As such, a reader often comes across resources that explain the Blockchain technology from a certain perspective only, leaving the reader with more questions than before. We will offer a holistic view on Blockchain. Starting with a brief history, we will give the building blocks of Blockchain, and explain their interactions. As graph mining has become a major part its analysis, we will elaborate on graph theoretical aspects of the Blockchain technology. We also devote a section to the future of Blockchain and explain how extensions like Smart Contracts and De-centralized Autonomous Organizations will function. Without assuming any reader expertise, our aim is to provide a concise but complete description of the Blockchain technology.Comment: 16 pages, 8 figure

    From the morality of living to the morality of sying: hunger strikes in Turkish prisons

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    Political hunger strikes have been part of the debates on human rights in many countries around the world. This paper explores the preconditions for and motives behind hunger strikes in Turkey by conceiving the hunger strikers as a part of citizenship politics through which strikers not only express their views against certain common issues, but also declare total opposition to an unjust condition within their political community. The paper focuses on the question of why some such “citizens” choose to participate in hunger strikes, which appears as an individual commitment to achieve a certain common objective. In doing so, the meaning of the experiences of hunger strikers and their universal right to live are elaborated in relation to their political and moral views. Hunger strikes are suggested to be seen as voluntary fasting, undertaken as a means of civil disobedience against an injustice within the context of citizenship. As examples of non-violent political acts, hunger strikes are not only part of citizenship politics but also expressions of commitment to achieving one’s goals through non-aggressive means for the common good of all citizens. Moreover, they can also be considered examples of martyrdom/heroism because hunger strikers altruistically risk their life for a public cause. As a particular altruistic act, hunger strikes can also be viewed as an effective form of communication directed toward fellow citizens. Moreover, they are expressions of self-determination for having control over and for one’s own life conditions. Finally, hunger strikes can be conceptualized as a struggle for transforming the configuration of structures and practices of citizenship about which one is passionately concerned. In this context, hunger strikes seem to be struggles for recognition in a relationship between two subjects, in which one subordinates the other

    An evaluation of indirect taxes in Turkey

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    The share of indirect taxes in tax revenues, specifically consumption taxes, is quite high in Turkey when compared to other OECD economies. This emphasis on indirect taxes in Turkey, as well as other developing economies, is argued to emerge from the inability of the government to collect direct taxes because of the existence of a large informal sector that is not easily taxable. It has been suggested that the recent increase in the indirect taxes puts the burden on mostly the poor, raising concerns of inequality. This paper evaluates the efficiency of the current indirect taxes in Turkey by taking into account distributional concerns. Using data from the 2003 Household Budget Survey, we estimate elasticities of different consumption goods and services using AIDS method. We then perform a marginal tax reform analysis to assess the efficiency of indirect taxes. Our findings indicate that there is room for improvement and the current tax rates are not optimal.Indirect taxes; Household survey; Marginal tax reform; AIDS estimation

    Improving High Resolution Histology Image Classification with Deep Spatial Fusion Network

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    Histology imaging is an essential diagnosis method to finalize the grade and stage of cancer of different tissues, especially for breast cancer diagnosis. Specialists often disagree on the final diagnosis on biopsy tissue due to the complex morphological variety. Although convolutional neural networks (CNN) have advantages in extracting discriminative features in image classification, directly training a CNN on high resolution histology images is computationally infeasible currently. Besides, inconsistent discriminative features often distribute over the whole histology image, which incurs challenges in patch-based CNN classification method. In this paper, we propose a novel architecture for automatic classification of high resolution histology images. First, an adapted residual network is employed to explore hierarchical features without attenuation. Second, we develop a robust deep fusion network to utilize the spatial relationship between patches and learn to correct the prediction bias generated from inconsistent discriminative feature distribution. The proposed method is evaluated using 10-fold cross-validation on 400 high resolution breast histology images with balanced labels and reports 95% accuracy on 4-class classification and 98.5% accuracy, 99.6% AUC on 2-class classification (carcinoma and non-carcinoma), which substantially outperforms previous methods and close to pathologist performance.Comment: 8 pages, MICCAI workshop preceeding

    MAMUD : contribution of HR satellite imagery to a better monitoring, modeling and understanding of urban dynamics

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    In this treatise the discussion of a methodology and results of semi-automatic city DSM extrac-tion from an Ikonos triplet, is introduced. Built-up areas are known as being complex for photogrammetric purposes, partly because of the steep changes in elevation caused by buildings and urban features. To make DSM extraction more robust and to cope with the specific problems of height displacement, concealed areas and shadow, a multi-image based approach is followed. For the VHR tri-stereoscopic study an area extending from the centre of Istanbul to the urban fringe is chosen. Research will concentrate, in first phase on the development of methods to optimize the extraction of photogrammetric products from the bundled Ikonos triplet. Optimal methods need to be found to improve the radiometry and geometry of the imagery, to improve the semi-automatically derivation of DSM’s and to improve the postprocessing of the products. Secondly we will also investigate the possibilities of creating stereo models out of images from the same sensor taken on a different date, e.g. one image of the stereo pair combined with the third image. Finally the photogrammetric products derived from the Ikonos stereo pair as well as the products created out of the triplet and the constructed stereo models will be investigated by comparison with a 3D reference. This evaluation should show the increase of accuracy when multi-imagery is used instead of stereo pairs
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