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21.
Web spam denotes the manipulation of web pages with the sole intent to raise their position in search engine rankings. Since
a better position in the rankings directly and positively affects the number of visits to a site, attackers use different
techniques to boost their pages to higher ranks. In the best case, web spam pages are a nuisance that provide undeserved advertisement
revenues to the page owners. In the worst case, these pages pose a threat to Internet users by hosting malicious content and
launching drive-by attacks against unsuspecting victims. When successful, these drive-by attacks then install malware on the
victims’ machines. In this paper, we introduce an approach to detect web spam pages in the list of results that are returned
by a search engine. In a first step, we determine the importance of different page features to the ranking in search engine
results. Based on this information, we develop a classification technique that uses important features to successfully distinguish
spam sites from legitimate entries. By removing spam sites from the results, more slots are available to links that point
to pages with useful content. Additionally, and more importantly, the threat posed by malicious web sites can be mitigated,
reducing the risk for users to get infected by malicious code that spreads via drive-by attacks. 相似文献
22.
Koordination in Service Value Networks 总被引:1,自引:1,他引:0
Benjamin Blau Clemens van Dinther Tobias Conte Yongchun Xu Christof Weinhardt 《WIRTSCHAFTSINFORMATIK》2009,51(5):398-413
The fundamental paradigm shift from traditional value chains to agile service value networks implies new economic and organizational challenges. As coordination mechanisms, auctions have proven to perform quite well in situations where intangible and heterogeneous goods are traded. Nevertheless, traditional approaches in the area of multidimensional combinatorial auctions are not quite suitable to enable the trade of composite services. A flawless service execution and therefore the requester’s valuation highly depends on the accurate sequence of the functional parts of the composition, meaning that in contrary to service bundles, composite services only generate value through a valid order of their components. The authors present an abstract model as a formalization of service value networks. The model comprehends a graph-based mechanism implementation to allocate multidimensional service offers within the network, to impose penalties for non-performance and to determine prices for complex services. The mechanism and the bidding language support various types of QoS attributes and their (semantic) aggregation. It is analytically shown that this variant is incentive compatible with respect to all dimensions of the service offer (quality and price). Based on these results, the authors numerically analyze strategic behavior of participating service providers regarding possible collusion strategies. 相似文献
23.
Real-time scheduling for energy harvesting sensor nodes 总被引:1,自引:1,他引:0
Energy harvesting has recently emerged as a feasible option to increase the operating time of sensor networks. If each node
of the network, however, is powered by a fluctuating energy source, common power management solutions have to be reconceived.
This holds in particular if real-time responsiveness of a given application has to be guaranteed. Task scheduling at the single
nodes should account for the properties of the energy source, capacity of the energy storage as well as deadlines of the single
tasks. We show that conventional scheduling algorithms (like e.g. EDF) are not suitable for this scenario. Based on this motivation,
we have constructed optimal scheduling algorithms that jointly handle constraints from both energy and time domain. Further
we present an admittance test that decides for arbitrary task sets, whether they can be scheduled without deadline violations.
To this end, we introduce the concept of energy variability characterization curves (EVCC) which nicely captures the dynamics
of various energy sources. Simulation results show that our algorithms allow significant reductions of the battery size compared
to Earliest Deadline First scheduling.
相似文献
Clemens MoserEmail: |
24.
This paper assesses the influence of (differential) settlement on sewer system functioning. Based on historical data of the vertical position of sewer invert levels, tilt measurements and in-sewer inspection videos, settlement and settlement related influences are analyzed for a case study area in Amsterdam. The average settlement rate of this system was 4 mm/year. Given this settlement rate, it is shown that settlement significantly influences sewer system functioning within the lifetime of a sewer (system). 相似文献
25.
Peter Lassig Hermann-Josef Lamberti Prof. Dr. Clemens Jochum 《WIRTSCHAFTSINFORMATIK》2003,45(2):147-156
Scoring and double-sided due diligence processes employed with vendor selection for IT infrastructure outsourcing Outsourcing opens the procurement of semi-finished products from business partners that are able to provide the respective processes in the required quality but at lower prices, e. g. because of bundling effects and specialization advantages. In particular, services that are not based on core-processes of an enterprise are well-suited for outsourcing. The evaluation of IT service outsourcing is difficult, because of its strategic position in enterprises. Against this background, this article describes a method to select a suitable vendor for IT infrastructure outsourcing employing scoring and double-sided due diligence processes. Our findings are based on experiences when selecting the vendor for outsourcing the European Information Technology Infrastructure (IT/I) area of the Deutsche Bank AG. 相似文献
26.
27.
Noemie van Garderen Frank J. Clemens Christos G. Aneziris Thomas Graule 《Ceramics International》2012,38(7):5481-5492
γ-Alumina extrudates for chemical-looping combustion in fluidized bed reactors were shaped by varying acetic acid concentrations between 0.07 and 3.76 M. Influence of pseudo-boehmite peptization on structural properties, microstructure, chemical phases and attrition resistance was determined. With addition of acetic acid, the d90 of boehmite agglomerates after 1 h kneading decreased from 134 to 40 μm at pH 4. Due to this, the extrusion diameter was reduced from 1500 to 200 μm, as well as median pore radii (from 30.1 to 5.3 nm). Porosity was about 70%. Addition of more than 1.87 M acid lead to a slight increase in mesopore sizes caused by some pore blocking caused by the formation of aluminium acetate salts. A small micropore surface was determined with t-layer model from Harkins and Jura. Higher attrition resistance was observed for samples peptized with lower acid concentration because of the closer contact between particles after decomposition. 相似文献
28.
Vassiliki Damakoudi Tobias Feldner Edina Dilji Andrey Belkin Prof. Clemens Richert 《Chembiochem : a European journal of chemical biology》2021,22(5):924-930
Messenger RNA (mRNA) is emerging as an attractive biopolymer for therapy and vaccination. To become suitable for vaccination, mRNA is usually converted to a biomaterial, using cationic peptides, polymers or lipids. An alternative form of converting mRNA into a material is demonstrated that uses branched oligoribonucleotide hybrids with the ability to hybridize with one or more regions of the mRNA sequence. Two such hybrids with hexamer arms and adamantane tetraol as branching element were prepared by solution-phase synthesis. When a rabies mRNA was treated with the branched hybrids at 1 M NaCl concentration, biomaterials formed that contained both of the nucleic acids. These results show that branched oligoribonucleotides are an alternative to the often toxic reagents commonly used to formulate mRNA for medical applications. 相似文献
29.
30.
Moritz Riebisch Philipp Weiß Clemens Cremer Ibrahim Aboulkhair Andreas Bührig-Polaczek 《Materials Science & Technology》2018,34(6):725-730
Solid solution-strengthened ductile iron (DI) exhibits outstanding mechanical properties due to the high silicon content. The strengthening by silicon addition is limited since additions above 4.3?wt-% lead to embrittlement. For a further improvement of mechanical properties, other alloying elements need to be considered. In the present work, the effect of various copper additions on the microstructure and the mechanical properties of solid solution-strengthened DI were investigated. The results show that no appreciable strengthening can be achieved by copper addition without the formation of pearlite in the matrix. The pearlite content increases considerably for Cu-additions above 0.23?wt-% and is independent of the cooling rate for the cooling conditions analysed. 相似文献