Biblio

Question Answering system(QA) plays an increasingly important role in the Internet age. The proportion of using the QA is getting higher and higher for the Internet users to obtain knowledge and solve problems, especially in the modern agricultural filed. However, the answer quality in QA varies widely due to the agricultural expert's level. Answer quality assessment is important. Due to the lexical gap between questions and answers, the existing approaches are not quite satisfactory. A practical approach RCAS is proposed to rank the candidate answers, which utilizes the support sets to reduce the impact of lexical gap between questions and answers. Firstly, Similar questions are retrieved and support sets are produced with their high-quality answers. Based on the assumption that high quality answers would also have intrinsic similarity, the quality of candidate answers are then evaluated through their distance from the support sets. Secondly, Different from the existing approaches, previous knowledge from similar question-answer pairs are used to bridge the straight lexical and semantic gaps between questions and answers. Experiments are implemented on approximately 0.15 million question-answer pairs about agriculture, dietetics and food from Yahoo! Answers. The results show that our approach can rank the candidate answers more precisely.

NoSQL databases have become popular with enterprises due to their scalable and flexible storage management of big data. Nevertheless, their popularity also brings up security concerns. Most NoSQL databases lacked secure data encryption, relying on developers to implement cryptographic methods at application level or middleware layer as a wrapper around the database. While this approach protects the integrity of data, it increases the difficulty of executing queries. We were motivated to design a system that not only provides NoSQL databases with the necessary data security, but also supports the execution of query over encrypted data. Furthermore, how to exploit the distributed fashion of NoSQL databases to deliver high performance and scalability with massive client accesses is another important challenge. In this research, we introduce Crypt-NoSQL, the first prototype to support execution of query over encrypted data on NoSQL databases with high performance. Three different models of Crypt-NoSQL were proposed and performance was evaluated with Yahoo! Cloud Service Benchmark (YCSB) considering an enormous number of clients. Our experimental results show that Crypt-NoSQL can process queries over encrypted data with high performance and scalability. A guidance of establishing service level agreement (SLA) for Crypt-NoSQL as a cloud service is also proposed.

Revolution in the field of technology leads to the development of cloud computing which delivers on-demand and easy access to the large shared pools of online stored data, softwares and applications. It has changed the way of utilizing the IT resources but at the compromised cost of security breaches as well such as phishing attacks, impersonation, lack of confidentiality and integrity. Thus this research work deals with the core problem of providing absolute security to the mobile consumers of public cloud to improve the mobility of user's, accessing data stored on public cloud securely using tokens without depending upon the third party to generate them. This paper presents the approach of simplifying the process of authenticating and authorizing the mobile user's by implementing middleware-centric framework called MiLAMob model with the huge online data storage system i.e. HDFS. It allows the consumer's to access the data from HDFS via mobiles or through the social networking sites eg. facebook, gmail, yahoo etc using OAuth 2.0 protocol. For authentication, the tokens are generated using one-time password generation technique and then encrypting them using AES method. By implementing the flexible user based policies and standards, this model improves the authorization process.