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Procedia - Social and Behavioral sciences 2012年 46卷 2297-2301页

作者： Ciobanu (defta) Costinela-Luminiţa Ciobanu (Iacob) Nicoleta-Magdalena Ph.D. student Faculty of Mathematics and Computer Science/Department of Computer Science University of Pitesti Targu din Vale Street No.1 Arges and Postcode 110040 Romania

Because more and more people are taking online courses, we need to understand the security issues of e-learning. The security aspect is even more important for the companies which use e-learning systems to deliver training courses to their employees. E-learning is a new method of learning which depends on the Internet in its execution, and is well known that Internet has become the venue for a new set of illegal activities, so e-learning environment is exposed to such threats. Information security can be obtained using methods such as cryptography, network protocols and others. In this paper we will discuss the typical threats of e-learning systems and we will see how we can address these issues. We will also discuss the security and privacy vulnerabilities of the most popular open-source e-learning systems, Moodle.

关键词： e-learning vulnerabilities education security Moodle

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Synchronous Partial Replication – Case Study: Implementing e-Learning Platform in an Academic Environment

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Procedia - Social and Behavioral sciences 2012年 46卷 1522-1526页

作者： Ciobanu (Iacob) Nicoleta - Magdalena Ciobanu (defta) Costinela Luminiţa Ph.D. student Faculty of Mathematics and Computer Science/Department of Computer Science University of Pitesti Targu din Vale Street No.1 Arges and Postcode 110040 Romania Faculty of Touristic and Commercial Management “Dimitrie Cantemir” Christian University Unirii Blvd No 176 District 4 Bucharest Romania

Replication is the key factor in improving availability, fault-tolerance and accessibility of data in all types of distributed systems. Replicated data is stored at multiple sites so that it can be used even when some copies are not available due to site failures and databases are kept synchronized to maintain consistency. The scope of distributing these replicas is local data processing. This paper describes the importance of synchronous partial replication, implementation and query optimization steps using Oracle technology for an E-learning portal of a university with geographically distributed locations.

关键词： distributed databases replication methods strategies

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The Replication Technology in E-learning Systems

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Procedia - Social and Behavioral sciences 2011年 28卷 231-235页

作者： Iacob (Ciobanu) Nicoleta – Magdalena Ph.D. student Faculty of Mathematics - Computer Science /Department of Computer Science University of Pitesti Str. Targu din Vale nr.1 Arges and Postcode 110040 Romania

The distributed systems are attractive for the users with various, interactive activities that require large processing capabilities, resource sharing and high availability. This paper presents the advantages of e-Learning education and focus on the importance of data replication in the design of a distributed database system that an e-learning portal uses. In addition, we analyze the available methods and strategies of data replication depending on needs, for improving performance and increasing data availability. The purpose of this paper is to present the advantages of using data replication technology in e-learning systems by universities with geographically distributed locations.

关键词： e-Learning distributed databases fragmentation replication allocation methods strategies

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distributed Queries in the E-learning Environment

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Procedia - Social and Behavioral sciences 2011年 28卷 241-245页

This paper presents the advantages of e-Learning education and focus on query processing in distributed databases. For this, we present the factors that influence distributed query optimization and examine the optimization strategies of query execution. The goal of this paper is to present strategies of optimizing query execution in e-learning systems used mainly by universities with geographically distributed locations, in order to obtain a system response time as low as possible and to minimize the total cost of implementation.

关键词： e-Learning distributed databases queries factors strategies

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The Broad Institute-Six Years Later

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CHEMISTRY & BIOLOGY 2010年第4期17卷 311-312页

作者： McCarthy, Alice Main Text “In June 2003 the scientific and medical communities at MIT Harvard University and its affiliated hospitals and the Whitehead Institute banded together as collaborating partners to form the Eli and Edythe L. Broad Institute based in Cambridge MA. The Broad Institute established with initial funding from a $100 million philanthropic donation from the Los Angeles-based Broad family was primarily viewed as a marriage between the Whitehead Institute's Center for Genome Research (WICGR) and the Harvard Institute of Chemistry and Cell Biology (ICCB). Eli Broad founder and chairman of AIG SunAmerica Inc. explained “the purpose of the Broad Institute is to create a new type of research institute to build on the accomplishments of the human genome project and to move to clinical applications to both prevent and cure diseases.” Every Thursday morning we meet with perhaps 20 faculty members and 100 other researchers to discuss what we're all doing and should be doing next. -David Altschuler This paragraph was written five years ago when the Broad Institute was in its very earliest days as a life science research community (McCarthy 2005). Since that time “the Broad” as it's known has kept true to Eli Broad's vision having attracted a talented group of researchers faculty trainees and professional staff. This 1600 person research community known internally as “Broadies” includes faculty staff and students from throughout the MIT and Harvard biomedical research communities and beyond with collaborations spanning over a hundred private and public institutions in more than 40 countries worldwide. “What is special about the Broad is that we have people from Harvard MIT and the Harvard hospitals come together and work on problems of shared interest that could not be solved in their own individuals labs” explains David Altshuler M.D. Ph.D. Deputy Director and one of the Broad's six core faculty members. “These problems require expertise beyond any one principal investigator and in

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Additive preconditioning in matrix computations

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PAMM 2008年第1期7卷

作者： V. Y. Pan B. Murphy R.E. Rosholt d. Ivolgin G. Qian I. Taj-Eddin Y. Tang X. Yan Department of Mathematics and Computer Science Lehman College of the City University of New York Bronx NY 10468 USA Ph.D. Program in Computer Science The City University of New York New York NY 10016 USA

We combine our novel SVd-free additive preconditioning with aggregation and other relevant techniques to facilitate the solution of a linear system of equations and other fundamental matrix computations. Our analysis and experiments show the power of our algorithms, guide us in selecting most effective policies of preconditioning and aggregation, and provide some new insights into these and related subjects. Compared to the popular SVd-based multiplicative preconditioners, our additive preconditioners are generated more readily and for a much larger class of matrices. Furthermore, they better preserve matrix structure and sparseness and have a wider range of applications (e.g., they facilitate the solution of a consistent singular linear system of equations and of the eigen-problem). (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

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Null space and eigenspace computations with additive preprocessing

Null space and eigenspace computations with additive preproc...

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SNC'07 - 2007 International Workshop on Symbolic-Numeric Computation

作者： Pan, Victor Y. Yan, Xiaodong Department of Mathematics and Computer Science Lehman College City University of New York Bronx NY 10468 United States Ph.D. Program in Computer Science City University of New York New York NY 10036 United States

ISBN: (纸本)1595937447

We propose and analyze additive preprocessing for computing a vector in the null space of a matrix and a basis for this space. due to our preprocessing, instead of singular linear systems we solve nonsingular ones, which preserve the conditioning properties and the structure of the input matrices. We extend our preprocessing to decrease the size and the condition number of an ill conditioned input matrix. We also cover applications to the eigenspace computations and to generating effective preconditioners for a linear system of equations. Copyright 2007 ACM.

关键词： Eigenvalues and eigenfunctions

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Real root-finding

Real root-finding

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SNC'07 - 2007 International Workshop on Symbolic-Numeric Computation

作者： Pan, Victor Y. Murphy, Brian Rosholt, Rhys Eric Qian, Guoliang Tang, Yuqing Department of Mathematics and Computer Science Lehman College City University of New York Bronx NY 10468 United States Ph.D. Program in Computer Science City University of New York New York NY 10036 United States

ISBN: (纸本)1595937447

In this paper we seek all real roots of a polynomial with real coefficients and real and nonreal roots. Somewhat paradoxically, one of the most effective solutions is by approximating these real roots semi-numerically together with all nonreal roots. Alternative methods are symbolic, based on descartes' rule of signs (which can be combined with the continued fraction approximation algorithm) or the Sturm (or Sturm-Habicht) sequences. We combine various old and new techniques to devise semi-numerical algorithms that are effective where the real roots do not lie near the nonreal ones. Copyright 2007 ACM.

关键词： Polynomials

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Order-computable sets

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Notre dame Journal of Formal Logic 2007年第3期48卷 317-347页

作者： Hirschfeldt, denis Miller, Russell Podzorov, Sergei Department of Mathematics University of Chicago Chicago IL 60637 5734 S University Ave United States Department of Mathematics Queens College-CUNY Flushing NY 11367 65-30 Kissena Blvd United States Ph.D. Program in Computer Science Graduate Center of CUNY New York NY 10016 365 Fifth Avenue United States Department of Mechanics and Mathematics Novosibirsk State University Novosibirsk 630090 Pirogova St 2 Russian Federation

We give a straightforward computable-model-theoretic definition of a property of Δ02 sets called order-computability. We then prove various results about these sets which suggest that, simple though the definition is... 详细信息

We give a straightforward computable-model-theoretic definition of a property of Δ⁰2 sets called order-computability. We then prove various results about these sets which suggest that, simple though the definition is, the property defies any easy characterization in pure computability theory. The most striking example is the construction of two computably isomorphic ce. sets, one of which is order-computable and the other not. © 2007 University of Notre dame.

关键词： Computable model theory Limitwise-monotonic functions Order-computability

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TRACKING CONTROL IN THE PRESENCE OF NONLINEAR dYNAMIC FRICTIONAL EFFECTS: ROBOT EXTENSION

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Asian Journal of Control 2008年第3期1卷

作者： M. Feemster d.M. dawson A. Behal W. dixon Matthew Feemster received the B.S degree in Electrical Engineering from Clemson University Clemson South Carolina in December 1994. Upon graduation he remained at Clemson University and received the M.S. degree in Electrical Engineering in 1997. During this time he also served as a research/teaching assistant. His research work focused on the design and implementation of various nonlinear control algorithms with emphasis on the induction motor and mechanical systems with friction present. He is currently working toward his Ph.D. degree in Electrical Engineering at Clemson University. Darren M. Dawson was born in 1962 in Macon Georgia. He received an Associate Degree in Mathematics from Macon Junior College in 1982 and a B.S. Degree in Electrical Engineering from the Georgia Institute of Technology in 1984. He then worked for Westinghouse as a control engineer from 1985 to 1987. In 1987 he returned to the Georgia Institute of Technology where he received the Ph.D. Degree in Electrical Engineering in March 1990. During this time he also served as a research/teaching assistant. In July 1990 he joined the Electrical and Computer Engineering Department and the Center for Advanced Manufacturing (CAM) at Clemson University where he currently holds the position of Professor. Under the CAM director's supervision he currently leads the Robotics and Manufacturing Automation Laboratory which is jointly operated by the Electrical and Mechanical Engineering departments. His main research interests are in the fields of nonlinear based robust adaptive and learning control with application to electro-mechanical systems including robot manipulators motor drives magnetic bearings flexible cables flexible beams and high-speed transport systems. Aman Behal was born in India in 1973. He received his Masters Degree in Electrical Engineering from Indian Institute of Technology Bombay in 1996. He is currently working towards a Ph.D in Controls and Robotics at Clemson University. His research focuses on the control of no

In this paper, we extend the observer/control strategies previously published in [25] to an n -link, serially connected, direct drive, rigid link, revolute robot operating in the presence of nonlinear friction effects modeled by the Lu-Gre model. In addition, we also present a new adaptive control technique for compensating for the nonlinear parameterizable Stribeck effects. Specifically, an adaptive observer/controller scheme is developed which contains a feedforward approximation of the Stribeck effects. This feedforward approximation is used in a composite controller/observer strategy which forces the average square integral of the position tracking error to an arbitrarily small value. Experimental results are included to illustrate the performance of the proposed controllers.

关键词： Friction compensation nonlinear control

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