1,721,150 research outputs found
Fine-grain watermarking for intellectual property protection
Full text linkThe current online digital world, consisting of thousands of newspapers, blogs, social media, and cloud file sharing services, is providing easy and unlimited access to a large treasure of text contents. Making copies of these text contents is simple and virtually costless. As a result, producers and owners of text content are interested in the protection of their intellectual property (IP) rights. Digital watermarking has become crucially important in the protection of digital contents. Out of all, text watermarking poses many challenges, since text is characterized by a low capacity to embed a watermark and allows only a restricted number of alternative syntactic and semantic permutations. This becomes even harder when authors want to protect not just a whole book or article, but each single sentence or paragraph, a problem well known to copyright law. In this paper, we present a fine-grain text watermarking method that protects even small portions of the digital content. The core method is based on homoglyph characters substitution for latin symbols and whitespaces. It allows to produce a watermarked version of the original text, preserving the anonymity of the users according to the right to privacy. In particular, the embedding and extraction algorithms allow to continuously protect the watermark through the whole document in a fine-grain fashion. It ensures visual indistinguishability and length preservation, meaning that it does not cause overhead to the original document, and it is robust to the copy and past of small excerpts of the text. We use a real dataset of 1.8 million New York articles to evaluate our method. We evaluate and compare the robustness against common attacks, and we propose a new measure for partial copy and paste robustness. The results show the effectiveness of our approach providing an average length of 101 characters needed to embed the watermark and allowing to protect paragraph-long excerpt or smaller the 94.5% of the times
Euler inverse axisymmetric solution for design of axial flow multistage turbomachinery
No full textAn axisymmetric model is used that replaces the blades with hub-to-tip streamsurfaces and their main effects on the flow with blade force terms. Euler equations are solved by means of an upwind finite-volume scheme for a specified swirl distribution in the meridional blade regions. This quantity drives the spanwise distribution of specific work for rotors and the swirl adding/removing property for stators. The time-marching procedure includes an evolutionary equation for the hub-to-tip geometry in each blade region. This equation involves use of a specified leading edge as a blade stacking line. Throughout the computation, the streamsurfaces take that shape providing the desired swirl distribution. The method is suitable to highly loaded blades i.e. turbine design. Compared to a traditional through-flow method, it predicts the overall turbine performances with about a 1% error. A satisfactory agreement is found concerning the spanwise distribution of the core flow quantities as well.</jats:p
A Numerical Smith Diagram Revision for Modern Low Pressure Turbine Profiles
No full textSmith diagram is historically one of the standard tools used
for turbine design, especially in concept design phase (CD) and
for assessment/comparison of turbine configurations. For each
turbomachinery stage, this graph provides a relation among
stage loading factor (y), flow coefficient (f) and aerodynamic
performance (). However, various essential inputs such as
stage reactions (R), aspect ratios (AR) or Reynolds numbers
(Re), or outputs like flow deflections (d), profile weights and
stresses are not directly taken into account.
In the work here presented, traditional loss correlation
models (Craig & Cox (C&C) and Ainley & Mathieson, Dunham
& Came, Kacker & Okapuu (AMDCKO)), are used to evaluate
stage performance and then to derive a more complete vision of
key parameters. Starting from a representative turbine
configuration, once some main characteristic boundary
conditions (BC) have been defined, few parameters are changed
in order to obtain a stage operating in a specific region of the
Smith diagram. By this way, it has been possible to compare
experimental data from original Smith with computational
results obtained with such approach. Moreover, additional
details previously missing (both aerodynamic and mechanical)
have been obtained and optimal design considerations have
been investigated under a multidisciplinary point of view.
In addiction, by means of dedicated tools, blade geometries
have been prepared for some of these configurations. Some
preliminary CFD 3D analyses have then been run to improve
specific understandings.
This research leads to extend Smith diagram with many
other important information for turbine module design and to
numerically revise the diagram itself, adjusting it with data
coming from modern high performance profile’s analyses
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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