Design issues and caching strategies for CD-ROM based multimedia storage

CD-ROMs have proliferated as a distribution media for desktop machines for a large variety of multimedia applications (targeted for a single-user environment) like encyclopedias, magazines and games. With CD-ROM capacities up to 3 GB being available in the near future, they will form an integral part of Video on Demand (VoD) servers to store full-length movies and multimedia. In the first section of this paper we look at issues related to the single- user desktop environment. Since these multimedia applications are highly interactive in nature, we take a pragmatic approach, and have made a detailed study of the multimedia application behavior in terms of the I/O request patterns generated to the CD-ROM subsystem by tracing these patterns. We discuss prefetch buffer design and seek time characteristics in the context of the analysis of these traces. We also propose an adaptive main-memory hosted cache that receives caching hints from the application to reduce the latency when the user moves from one node of the hyper graph to another. In the second section we look at the use of CD-ROM in a VoD server and discuss the problem of scheduling multiple request streams and buffer management in this scenario. We adapt the C-SCAN (Circular SCAN) algorithm to suit the CD-ROM drive characteristics and prove that it is optimal in terms of buffer size management. We provide computationally inexpensive relations by which this algorithm can be implemented. We then propose an admission control algorithm which admits new request streams without disrupting the continuity of playback of the previous request streams. The algorithm also supports operations such as fast forward and replay. Finally, we discuss the problem of optimal placement of MPEG streams on CD-ROMs in the third section.

On the Implementation of a Streaming Video over Peer to Peer network using Middleware Components

Video streaming applications have hitherto been supported by single server systems. A major drawback of such a solution is that it increases the server load. The server restricts the number of clients that can be simultaneously supported due to limitation in bandwidth. The constraints of a single server system can be overcome in video streaming if we exploit the endless resources available in a distributed and networked system. We explore a P2P system for streaming video applications. In this paper we build a P2P streaming video (SVP2P) service in which multiple peers co-operate to serve video segments for new requests, thereby reducing server load and bandwidth used. Our simulation shows the playback latency using SVP2P is roughly 1/4th of the latency incurred when the server directly streams the video. Bandwidth consumed for control messages (overhead) is as low as 1.5% of the total data transfered. The most important observation is that the capacity of the SVP2P grows dynamically.

Females of a tree cricket prefer larger males but not the lower frequency male calls that indicate large body size

In the tree cricket Oecanthus henryi, females are attracted by male calls and can choose between males. To make a case for female choice based on male calls, it is necessary to examine male call variation in the field and identify repeatable call features that are reliable indicators of male size or symmetry. Female preference for these reliable call features and the underlying assumption behind this choice, female preference for larger males, also need to be examined. We found that females did prefer larger males during mating, as revealed by the longer mating durations and longer spermatophore retention times. We then examined the correlation between acoustic and morphological features and the repeatability of male calls in the field across two temporal scales, within and across nights. We found that carrier frequency was a reliable indicator of male size, with larger males calling at lower frequencies at a given temperature. Simultaneous playback of male calls differing in frequency, spanning the entire range of natural variation at a given temperature, revealed a lack of female preference for low carrier frequencies. The contrasting results between the phonotaxis and mating experiments may be because females are incapable of discriminating small differences in frequency or because the change in call carrier frequency with temperature renders this cue unreliable in tree crickets. (C) 2012 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

QUAD: quality assessment of documents

We propose a set of metrics that evaluate the uniformity, sharpness, continuity, noise, stroke width variance,pulse width ratio, transient pixels density, entropy and variance of components to quantify the quality of a document image. The measures are intended to be used in any optical character recognition (OCR) engine to a priori estimate the expected performance of the OCR. The suggested measures have been evaluated on many document images, which have different scripts. The quality of a document image is manually annotated by users to create a ground truth. The idea is to correlate the values of the measures with the user annotated data. If the measure calculated matches the annotated description,then the metric is accepted; else it is rejected. In the set of metrics proposed, some of them are accepted and the rest are rejected. We have defined metrics that are easily estimatable. The metrics proposed in this paper are based on the feedback of homely grown OCR engines for Indic (Tamil and Kannada) languages. The metrics are independent of the scripts, and depend only on the quality and age of the paper and the printing. Experiments and results for each proposed metric are discussed. Actual recognition of the printed text is not performed to evaluate the proposed metrics. Sometimes, a document image containing broken characters results in good document image as per the evaluated metrics, which is part of the unsolved challenges. The proposed measures work on gray scale document images and fail to provide reliable information on binarized document image.

Low embodied energy cement stabilised rammed earth building-A case study

Rammed earth is a monolithic construction and the construction process involves compaction of processed soil in progressive layers in a rigid formwork. Durable and thinner load bearing walls can be built using stabilised rammed earth. Use of inorganic additives such as cement for rammed earth walls has been in practice since the last 5-6 decades and cement stabilised rammed earth (CSRE) buildings can be seen across the world. The paper deals with the construction aspects, structural design and embodied energy analysis of a three storey load bearing school building complex. The CSRE school complex consists of 15 classrooms, an open air theatre and a service block. The complex has a built-up area of 1691.3 m(2) and was constructed employing manual construction techniques. This case study shows low embodied energy of 1.15 GJ/m(2) for the CSRE building as against 3-4 GJ/m(2) for conventional burnt clay brick load bearing masonry buildings. (C) 2013 Elsevier B.V. All rights reserved.

Silent katydid females are at higher risk of bat predation than acoustically signalling katydid males

Males that produce conspicuous mate attraction signals are often at high risk of predation from eavesdropping predators. Females of such species typically search for signalling males and their higher motility may also place them at risk. The relative predation risk faced by males and females in the context of mate-finding using long-distance signals has rarely been investigated. In this study, we show, using a combination of diet analysis and behavioural experiments, that katydid females, who do not produce acoustic signals, are at higher risk of predation from a major bat predator, Megaderma spasma, than calling males. Female katydids were represented in much higher numbers than males in the culled remains beneath roosts of M. spasma. Playback experiments using katydid calls revealed that male calls were approached in only about one-third of the trials overall, whereas tethered, flying katydids were always approached and attacked. Our results question the idea that necessary costs of mate-finding, including risk of predation, are higher in signalling males than in searching females.