Data warehouses offer a compromise between freshness of data and query evaluation times. However, a fixed preference ratio between these two variables is too undifferentiated. With our approach, clients submit a query together with an explicit freshness limit as a new Quality-of-Service parameter. Our architecture is a cluster of databases. The contribution of this article is the design, implem...

Energy and Privacy are the two important aspects in the Battery limited wireless sensor networks. Currently adopting hop by hop encryption for privacy preserving protocols are not efficient in terms of the energy and privacy in WSNs because these protocols decrypts and encrypts the data at the aggregator node since the decrypts at every aggregator node consumes more power and it also increases ...

Search engine quality is impacted by two factors: the quality of the ranking/matching algorithm used and the freshness of the search engine’s index, which maintains a “snapshot” of the Web. Web crawlers capture web pages and refresh the index, but this is always a never-ending quest, as web pages get updated frequently (and thus have to be re-crawled). Knowing when to re-crawl a web page is fun...

Wireless access points (WAPs) are devices that provide Internet connectivity to devices such as desktops, laptops, smartphones, and tablets. Hence, it is important to provide sufficient availability to devices and security for the traffic that is routed by a WAP. However, attackers can decrease the network bandwidth or obtain the traffic including private data such as search histories, login in...

Quality of Service (QoS) and Quality of Data (QoD) are the two major dimensions for evaluating any query processing system. In the context of data stream management systems (DSMSs), multi-query scheduling has been exploited to improve QoS. In this paper, we are proposing to exploit query scheduling to improve QoD in DSMSs. Specifically, we are presenting a new policy for scheduling multiple con...

We consider a cache updating system with source, and user. There are $n$ files. The source keeps the freshest version of files which updated known rates $\lambda _{i}$ . downloads from $c_{i}$ user gets updates $u_{i}$ When an update, it either fresh update or file at becomes outdated by in case update. find analytical expression for average freshness Next, we generalize our setting to where th...