There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Matrix Factorization Techniques for Recommender Systems

/pdf/a-break-in-the-clouds-towards-a-cloud-definition-svovsw1r5a.pdf

A Break in the Clouds: Towards a Cloud Definition

Network virtualization is recognized as an enabling technology for the future Internet. It aims to overcome the resistance of the current Internet to architectural change. Application of this technology relies on algorithms that can instantiate virtualized networks on a substrate infrastructure, optimizing the layout for service-relevant metrics. This class of algorithms is commonly known as "Virtual Network Embedding (VNE)" algorithms. This paper presents a survey of current research in the VNE area. Based upon a novel classification scheme for VNE algorithms a taxonomy of current approaches to the VNE problem is provided and opportunities for further research are discussed.

Virtual Network Embedding: A Survey

In the past five years there has been a dramatic increase in work on Search-Based Software Engineering (SBSE), an approach to Software Engineering (SE) in which Search-Based Optimization (SBO) algorithms are used to address problems in SE. SBSE has been applied to problems throughout the SE lifecycle, from requirements and project planning to maintenance and reengineering. The approach is attractive because it offers a suite of adaptive automated and semiautomated solutions in situations typified by large complex problem spaces with multiple competing and conflicting objectives.This article1 provides a review and classification of literature on SBSE. The work identifies research trends and relationships between the techniques applied and the applications to which they have been applied and highlights gaps in the literature and avenues for further research.

/pdf/search-based-software-engineering-trends-techniques-and-3b0bwaagfi.pdf

Search-based software engineering: Trends, techniques and applications

Blocking attack flows to protect the threatened resources is a necessary step in defending against the Distributed Denial-of-Service DDoS attacks. Two kinds of reactive packet filtering technologies have been proposed as close to victim-end filtering and close to source-ends filtering. The first scheme only involves a single Active Filtering Routers AFRs but damages the whole network bandwidth resource; another extreme scheme requires millions of AFRs and thus degrades the network transmission performance, but it has the best defense effect. A feasible scheme should use a certain quantity of AFRs to filter attack flows between the victim end and the source ends. Going one step further, in this paper, we make the first effort on studying the filtering location to maximize the protected network bandwidth while not permitting any attack flow to reach the victim. We formulate this problem to an integer linear programming problem and design an efficient heuristic filtering location algorithm. We evaluate our algorithm through integrating it into the existing filtering architecture and implementing this integration scheme on the emulated DDoS scenarios based on real-world Internet topology. Our evaluation results show that compared to the state-of-the-art source-ends filtering scheme Active Internet Traffic Filtering, this integration scheme only uses 20% of its AFRs to achieve more than 70% of its protection effect. Copyright © 2013 John Wiley & Sons, Ltd.

Filtering location optimization for the reactive packet filtering

With the opening up of the network capabilities, it became more and more important to manage service level agreement (SLA) between OSA operator and service provider strongly. Firstly, this paper proposed the content of SLA. Then the supporting mechanism of service level agreement in the standard of service level agreement in the open service access (OSA) platform, which is the standard of 3GPP as to open network capabilities, is fully given. However, the drawbacks of SLA in the OSA are emphasized. The improvement and future works are put forward at the end of the paper.

The study on improvement SLA of OSA

Community Question Answering (CQA) has increasingly become an important service for people asking questions and providing answers online, which enables people to help each other by sharing knowledge. Recently, with accumulation of users and contents, much concern has arisen over the efficiency and answer quality of CQA services. To address this problem, question routing has been proposed which aims at routing new questions to suitable answerers, who have both high possibility and high ability to answer the questions. In this paper, we formulate question routing as a multi-objective ranking problem, and present a multi-objective learning-to-rank approach for question routing (MLQR), which can simultaneously optimize the answering possibility and answer quality of routed users. In MLQR, realizing that questions are relatively short and usually attached with tags, we first propose a tagword topic model (TTM) to derive topical representations of questions. Based on TTM, we then develop features for each question-user pair, which are captured at both platform level and thread level. In particular, the platform-level features summarize the information of a user from his/her history posts in the CQA platform, while the thread-level features model the pairwise competitions of a user with others in his/her answered threads. Finally, we extend a state-of-the-art learning-to-rank algorithm for training a multi-objective ranking model. Extensive experimental results on real-world datasets show that our MLQR can outperform state-of-the-art methods in terms of both answering possibility and answer quality.

A Multi-Objective Optimization Approach for Question Routing in Community Question Answering Services (Extended Abstract)

Aiming at addressing disaster recovery issues in current Soft switch network, this paper proposed a novel method using P2P technologies, referred to as Remote Backup and Recovery based on Segmentation strategy (RBRS), which puts forwards a method of data segmentation and recovery dividing the backup data into equal parts and order stored in the extra-area. With the advent of a failure in a node, data and business can be recovered in another normal node. Some analyses have been put on data reliability of RBRS and system parameters. Our simulation results show that the strategy is simple yet efficient, with a certain slice numbers and redundant modulus RBRS guaranteeing the reliability of user data.

A Novel Disaster Recovery Strategy in NGN Core Network Based on P2P Technologies

Negotiation is a crucial stage of Web Services interaction lifecycle. By exchanging a sequence of proposals in the negotiation stage, a service provider and a consumer try to establish a formal contract, to specify agreed terms on the service, particularly terms on non-functional aspects. To react to an ever-changing environment, flexible negotiation strategies that can make adjustable rates of concession should be adopted. This paper presents such flexible strategies for Web Services negotiation. In a negotiation round, the negotiation strategies first examine the environment situations by evaluating certain factors, which include time, resources, number of counterparts and current proposals from the counterparts. For each factor, there is a corresponding function that suggests the amount of concession in terms of that factor. Then considering the importance of each service attribute, the target concession per attribute is determined. As a final step, a set of experimental tests is executed to evaluate the performance of the negotiation strategies.

Sen Su

Papers

Filtering location optimization for the reactive packet filtering

The study on improvement SLA of OSA

A Multi-Objective Optimization Approach for Question Routing in Community Question Answering Services (Extended Abstract)

A Novel Disaster Recovery Strategy in NGN Core Network Based on P2P Technologies

Flexible decision making in web services negotiation