7,080 research outputs found

    Mobile WiMAX: multi-cell network evaluation and capacity optimization

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    Automatically configuring parallelism for hybrid layouts

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    Distributed processing frameworks process data in parallel by dividing it into multiple partitions and each partition is processed in a separate task. The number of tasks is always created based on the total file size. However, this can lead to launch more tasks than needed in the case of hybrid layouts, because they help to read less data for certain operations (i.e., projection, selection). The over-provisioning of tasks may increase the job execution time and induce significant waste of computing resources. The latter due to the fact that each task introduces extra overhead (e.g., initialization, garbage collection, etc.). To allow a more efficient use of resources and reduce the job execution time, we propose a cost-based approach that decides the number of tasks based on the data being read. The proposed cost-model can be utilized in a multi-objective approach to decide both the number of tasks and number of machines for execution.Peer ReviewedPostprint (author's final draft

    The Best Answers? Think Twice: Online Detection of Commercial Campaigns in the CQA Forums

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    In an emerging trend, more and more Internet users search for information from Community Question and Answer (CQA) websites, as interactive communication in such websites provides users with a rare feeling of trust. More often than not, end users look for instant help when they browse the CQA websites for the best answers. Hence, it is imperative that they should be warned of any potential commercial campaigns hidden behind the answers. However, existing research focuses more on the quality of answers and does not meet the above need. In this paper, we develop a system that automatically analyzes the hidden patterns of commercial spam and raises alarms instantaneously to end users whenever a potential commercial campaign is detected. Our detection method integrates semantic analysis and posters' track records and utilizes the special features of CQA websites largely different from those in other types of forums such as microblogs or news reports. Our system is adaptive and accommodates new evidence uncovered by the detection algorithms over time. Validated with real-world trace data from a popular Chinese CQA website over a period of three months, our system shows great potential towards adaptive online detection of CQA spams.Comment: 9 pages, 10 figure

    Large eddy simulation of transverse single/double jet in supersonic crossflow

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    In this paper, large eddy simulation of transverse sonic single/double hydrogen jets into supersonic Mach 2 crossflow have been carried out to investigate the complex flow structures and the mixing performance. Detailed turbulence characteristics, in terms of the instantaneous and mean flow fields, the vortex structures and their evolutions, the turbulence kinetic energy and the Reynolds shear stress distributions, the maximum hydrogen mass fraction and jet penetration, have been provided. Results of the two-dimensional and three-dimensional streamlines illustrate that the trailing counter-rotating vortex pairs (TCVP), the secondary TCVP of primary jet and the horseshoe vortex can merge and form a new horseshoe vortex. Three counter-rotating vortex pairs (CVP) are formed in the downstream of secondary jet: the CVP-B due to interactions between the supersonic crossflow and secondary jet; the CVP-C due to interactions between the supersonic crossflow, primary and secondary jets; and the CVP-D due to interactions of the supersonic crossflow and primary jet. The presence of primary jet flow alters the Reynolds shear stress distributions after the secondary injection with the influence of these large-scale structures. In addition, the two-stage jet injection system is proved to yield a better mixing performance than the single jet system

    Benchmarking explanatory models for inertia forecasting using public data of the nordic area

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    This paper investigates the performance of a day-ahead explanatory model for inertia forecasting based on field data in the Nordic system, which achieves a 43% reduction in mean absolute percentage error (MAPE) against a state-of-the-art time-series forecast model. The generalizability of the explanatory model is verified by its consistent performance on Nordic and Great Britain datasets. Also, it appears that a long duration of training data is not required to obtain accurate results with this model, but taking a more spatially granular approach reduces the MAPE by 3.6%. Finally, two further model enhancements are studied considering the specific features in Nordic system: (i) a monthly interaction variable applied to the day-ahead national demand forecast feature, reducing the MAPE by up to 18%; and (ii) a feature based on the inertia from hydropower, although this has a negligible impact. The field dataset used for benchmarking is also made publicly available

    Roles of tumor suppressors in regulating tumor-associated inflammation.

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    Loss or silencing of tumor suppressors (TSs) promotes neoplastic transformation and malignant progression. To date, most work on TS has focused on their cell autonomous effects. Recent evidence, however, demonstrates an important noncell autonomous role for TS in the control of tumor-associated inflammation. We review evidence from clinical data sets and mouse model studies demonstrating enhanced inflammation and altered tumor microenvironment (TME) upon TS inactivation. We discuss clinical correlations between tumor-associated inflammation and inactivation of TS, and their therapeutic implications. This review sets forth the concept that TS can also suppress tumor-associated inflammation, a concept that provides new insights into tumor-host interactions. We also propose that in some cases the loss of TS function in cancer can be overcome through inhibition of the resulting inflammatory response, regardless whether it is a direct or an indirect consequence of TS loss

    The role of regulation in influencing income-generating activities among public sector doctors in Peru.

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    OBJECTIVE: To examine in Peru the nature of dual practice (doctors holding two jobs at once - usually public sector doctors with private practices), the factors that influence individuals' decisions to undertake dual practice, the conditions faced when doing so and the potential role of regulatory intervention in this area. METHODS: The study entailed qualitative interviews with a sample of twenty medical practitioners based in metropolitan Lima, representing a cross-section of those primarily employed in either the private or public sectors and engaged in clinical practice or policy making. The interviews focused on: 1. individuals' experience with dual practice; 2. the general underlying pressures that influence the nature and extent of such activities; and 3. attitudes toward, and the influence of, regulation on such activities. RESULTS: Dual practice is an activity that is widespread and well-accepted, and the prime personal motivation is financial. However, there are also a number of important broad macroeconomic influences on dual practice particularly the oversupply of medical services, the deregulated nature of this market, and the economic crisis throughout the country, which combine to create major hardships for those attempting to make a living through medical practice. There is some support among doctors for tighter regulation. CONCLUSION: Research findings suggest appropriate policy responses to dual practice involve tighter controls on the supply of medical practitioners; alleviation of financial pressures brought by macro-economic conditions; and closer regulation of such activities to ensure some degree of collective action over quality and the maintenance of professional reputations. Further research into this issue in rural areas is needed to ascertain the geographical generalizability of these policy responses

    Comparison of equalisation strategies for multi-carrier CDMA

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