No abstract

The development of proxy caching is essential in the area of video‐on‐demand (VoD) to meet users' expectations. VoD requires high bandwidth and creates high traffic due to the nature of media. Many researchers have developed proxy caching models to reduce bandwidth consumption and traffic. Proxy caching keeps part of a media object to meet the viewing expectations of users without delay and provides interactive playback. If the caching is done continuously, the entire cache space will be exhausted at one stage. Hence, the proxy server must apply cache replacement policies to replace existing objects and allocate the cache space for the incoming objects. Researchers have developed many cache replacement policies by considering several parameters, such as recency, access frequency, cost of retrieval, and size of the object. In this paper, the Weighted‐Rank Cache replacement Policy (WRCP) is proposed. This policy uses such parameters as access frequency, aging, and mean access gap ratio and such functions as size and cost of retrieval. The WRCP applies our previously developed proxy caching model, Hot‐Point Proxy, at four levels of replacement, depending on the cache requirement. Simulation results show that the WRCP outperforms our earlier model, the Dual Cache Replacement Policy.

Pollen morphology of 18 species from the genus Impatiens collected from different localities in Nilgiris, Tamil Nadu was evaluated using scanning electron microscopy (SEM) during the period of February 2017 to November 2019. From the observation of pollen it was found to be structurally monad; prolate, sub-prolate and prolate-spheroidal in equatorial view; and circular, rectangular, triangular, quinquangular, elliptic and quadrangular in polar view. The apertures varied from dicolpate, tricolpate to tetracolpate. The main ornamentation type was reticulate in most of the species except Impatiens fruticosa which showed echinate ornamentation. The variations in pollen structure within the species were useful for the identification and classification of the genus Impatiens. The high structural diversity renders important taxonomic value for species differentiation.