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101.
Ismail Omar Hababeh Muthu Ramachandran Nicholas Bowring 《The Journal of supercomputing》2007,39(1):3-18
Enhancing the performance of the DDBs (Distributed Database system) can be done by speeding up the computation of the data allocation, leading to higher speed allocation decisions and resulting
in smaller data redundancy and shorter processing time. This paper deals with an integrated method for grouping the distributed
sites into clusters and customizing the database fragments allocation to the clusters and their sites. We design a high speed
clustering and allocating method to determine which fragments would be allocated to which cluster and site so as to maintain
data availability and a constant systemic reliability, and evaluate the performance achieved by this method and demonstrate
its efficiency by means of tabular and graphical representation. We tested our method over different network sites and found
it reduces the data transferred between the sites during the execution time, minimizes the communication cost needed for processing
applications, and handles the database queries and meets their future needs. 相似文献
102.
Compacts made from chemically grade Fe2O3 were fired at 1473K for 6 hrs. The fired compacts were isothermally reduced either by hydrogen or carbon monoxide at 1073–1373K. The O2 weight‐loss resulting from the reduction process was continuously recorded as a function of time using TGA technique, whereas the volume change at different reduction conditions was measured by displacement method. Porosity measurements, microscopic examination and X‐ray diffraction analysis were used to characterize the fired and reduced products. The rate of reduction at both the initial and final stages was increased with temperature. The reduction mechanism deduced from the correlations between apparent activation energy values, structure of partially reduced compacts and application of gas‐solid reaction models revealed the reduction rate (dr/dt) at both the initial and final stages. At early stages, the reduction was controlled by a combined effect of gaseous diffusion and interfacial chemical reaction mechanism, while at the final stages the interfacial chemical reaction was the rate determining step. In H2 reduction, maximum swelling (80%) was obtained at 1373K, which was attributed to the formation of metallic iron plates. In CO reduction, catastrophic swelling (255%) was obtained at 1198K due to the formation of metallic iron plates and whiskers. 相似文献
103.
104.
Omar Tahri Helder Araujo François Chaumette Youcef Mezouar 《Robotics and Autonomous Systems》2013,61(12):1588-1600
This paper deals with the use of invariant visual features for visual servoing. New features are proposed to control the 6 degrees of freedom of a robotic system with better linearizing properties and robustness to noise than the state of the art in image-based visual servoing. We show in this paper that by using these features the behavior of image-based visual servoing in task space can be significantly improved. Several experimental results are provided and validate our proposal. 相似文献
105.
In this paper, we address the problem of clustering in Vehicular Ad hoc Networks (VANETs) using Quality of Service Optimized Link State Routing (QoS-OLSR) protocol. Several clustering algorithms have been proposed for VANET and MANET. However, the mobility-based algorithms ignore the Quality of Service requirements that are important for VANET safety, emergency, and multimedia services while the QoS-based algorithms ignore the high speed mobility constraints since they are dedicated for Mobile Ad hoc Networks (MANETs). Our solution is a new QoS-based clustering algorithm that considers a tradeoff between QoS requirements and high speed mobility constraints. The goal is to form stable clusters and maintain the stability during communications and link failures while satisfying the Quality of Service requirements. This is achieved by: (1) considering the high mobility metrics while computing the QoS, (2) using Ant Colony Optimization for MPRs selection, and (3) using MPR recovery algorithm able to select alternatives and keep the network connected in case of link failures. Performance analysis and simulation results show that the proposed model can maintain the network stability, reduce the end-to-end delay, increase the packet delivery ratio, and reduce the communications overhead. 相似文献
106.
Sazia Parvin Farookh Khadeer Hussain Omar Khadeer Hussain Thandar Thein Jong Sou Park 《Computing》2013,95(10-11):927-948
With the rapid growth of wireless communication, the deployment of cyber-physical system (CPS) is increasing day by day. As a cyber physical system involves a tight coupling between the physical and computational components, it is critical to ensure that the system, apart from being secure, is available for both the cyber and physical processes. Traditional methods have generally been employed to defend an infrastructure system against physical threats. However, this does not guarantee that the availability of the system will always be high. In this paper, we propose a multi-cyber (computational unit) framework to improve the availability of CPS based on Markov model. We evaluate the effectiveness of our proposed framework in terms of availability, downtime, downtime cost and reliability of the CPS framework. 相似文献
107.
This chapter examines issues concerned with supporting managers and organizations with information and communication technologies
as they decide and act in turbulent and high-velocity environments. In particular, the chapter identifies five key tensions
in this context: (1) the tension between the need for quick decisions and the need for analytical decision processes; (2)
the tension involving managerial need for action and the need for the safest execution of decisions that may be bold and risky;
(3) the tension around empowering middle managers and management teams at various organizational levels in the midst of powerful
and impatient top executives; (4) the tension between programmed, quick-action learning loops and the increased requirement
for emergence and improvisation; and (5) the tension between expending effort to eliminate the digital divide with other organizations
versus finding expedient ways to communicate through heterogeneous digital infrastructures. Each of the tensions, and how
it can be managed, is illustrated through a case example. The chapter ends by suggesting that the management of these critical
tensions needs to be fused into the day-to-day fabric of management practices for decision support processes.
This article is part of the “Handbook on Decision Support Systems” edited by Frada Burstein and Clyde W. Holsapple (2008)
Springer. 相似文献
108.
Yifeng Lei Omar F. Zouani Lila Rami Christel Chanseau Marie‐Christine Durrieu 《Small (Weinheim an der Bergstrasse, Germany)》2013,9(7):1086-1095
How endothelial cells (ECs) express the particular filopodial or lamellipodial form of the actin machinery is critical to understanding EC functions such as angiogenesis and sprouting. It is not known how these mechanisms coordinately promote lumen formation of ECs. Here, adhesion molecules (RGD peptides) and inductor molecules (BMP‐2 mimetic peptides) are micropatterned onto polymer surfaces by a photolithographic technique to induce filopodial and lamellipodial migration modes. Firstly, the effects of peptide microgeometrical distribution on EC adhesion, orientation and morphogenesis are evaluated. Large micropatterns (100 μm) promote EC orientation without lumen formation, whereas small micropatterns (10–50 μm) elicit a collective cell organization and induce EC lumen formation, in the case of RGD peptides. Secondly, the correlation between EC actin machinery expression and EC self‐assembly into lumen formation is addressed. Only the filopodial migration mode (mimicked by RGD) but not lamellipodial migration mode (mimicked by BMP‐2) promotes EC lumen formation. This work gives a new concept for the design of biomaterials for tissue engineering and may provide new insight for angiogenesis inhibition on tumors. 相似文献
109.
Microwave irradiation under different pH conditions induced a decrease in β-lactoglobulin antigenicity 总被引:1,自引:0,他引:1
Hadria Grar Hanane Kaddouri Hanane Gourine Hanane Negaoui Omar Kheroua Djamel Saïdi 《European Food Research and Technology》2009,229(5):779-783
Whey proteins adjusted at pH values 2, 4.6, 9 and at the natural milk pH (pH 6.8) were subjected to microwave irradiation
at 300 W for 20 min or 700 W for 10 min. The protein composition of treated and native whey proteins were evaluated by Lowry’s
method and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The ability of treated whey to bind IgG polyclonal
antibody was determined by an enzyme-linked immunosorbent assay (ELISA) using sera obtained from rabbit immunized to β-Lactoglobulin
(β-Lg). Significantly higher losses in soluble protein concentrations were observed for microwave irradiated whey proteins
at pH value 4.6 (35.6% at 300 W and 44.33% at 700 W) (P < 0.0001) compared with those irradiated at the natural milk pH (26% at 300 or 700 W). The electrophoretic patterns of these
proteins revealed a considerable decrease in intensity of the band corresponding to α-lactalbumin but only a slight modification
was observed for the electrophoretic profiles of β-lactoglobulin. The data obtained with a rabbit anti-β-lactoglobulin immunoglobulin
indicated a low antigenic response for microwave-irradiated whey proteins at the natural milk pH (up to 29.32% as well as
300–700 W) (P < 0.001). The lowest antigenicity was observed for samples adjusted to pH 4.6 followed by microwave irradiation at 300 or
700 W (46.99% at 300 W and 41.16% at 700 W) (P < 0.0001). 相似文献
110.
Steven Euijong Whang Omar Benjelloun Hector Garcia-Molina 《The VLDB Journal The International Journal on Very Large Data Bases》2009,18(6):1261-1277
Entity resolution (ER) (also known as deduplication or merge-purge) is a process of identifying records that refer to the same real-world entity and merging them together. In practice, ER results may contain “inconsistencies,” either due to mistakes by the match and merge function writers or changes in the application semantics. To remove the inconsistencies, we introduce “negative rules” that disallow inconsistencies in the ER solution (ER-N). A consistent solution is then derived based on the guidance from a domain expert. The inconsistencies can be resolved in several ways, leading to accurate solutions. We formalize ER-N, treating the match, merge, and negative rules as black boxes, which permits expressive and extensible ER-N solutions. We identify important properties for the rules that, if satisfied, enable less costly ER-N. We develop and evaluate two algorithms that find an ER-N solution based on guidance from the domain expert: the GNR algorithm that does not assume the properties and the ENR algorithm that exploits the properties. 相似文献