Sharif Digital Repository

Unlike those on Internet, the media providers on P2P networks are ordinary nodes with limited shared resources such as bandwidth. Multi-sender methods are the best existing solutions to video streaming on P2P networks. In this paper, we propose use of a multicast method on the top of an arbitrary multi-sender method so that all requesting peers receive almost the same expected bit-rate. Experimental results, derived from implementation of the proposed algorithm on Pastry P2P network confirm our claim. Another advantage of our method over the existing methods is its scalability with the number of receivers  

Optical coherence tomography (OCT) is a noninvasive imaging modality that provides cross-sectional images from microstructures of tissues. This optical imaging system works based on Michelson interferometry principle and has intermediate resolution and penetration depth which makes it appropriate for imaging thin tissues such as skin and eye. OCT images suffer from three main artifacts that make images difficult to be analyzed. The first one is small grainy structures called speckle which degrade image quality and decreases axial and lateral resolution. The second one is light intensity attenuation which is a function of depth. It happens because of absorbing and scattering nature of tissue... 

Almost all existing multi-description coding (MDC) schemes are designed for media streaming over Internet. In this work, a wavelet-based video MDC technique is introduced that fits the criteria of media streaming over peer-to-peer networks. Our proposed method assigns descriptions to the senders due to their characteristic (i.e. bandwidth and availability). In contrast to traditional MDC, different descriptions in the proposed method have different importance in remaking the original media. Our simulation results show considerable improvement of video quality at the receiver (up to 10 dB) as compared to the state-of-the-art. ©2007 IEEE  

The important problem of content location in an unstructured distributed network (such as P2P, with no central searching system, graph construction control or file placement regulation) is addressed. The existing methods that are based on either flooding or random walk impose a large traffic load on the network or require a long time to search. In this work, we propose a method that outperforms the existing methods in both of these measures. These advantages are achieved by publishing traces of the contents of each node in its nearby nodes, so that the closer nodes to the target have a stronger trace of it. Such traces are used to rapidly locate the desired content. The superb performance of... 

Due to the constraints of P2P networks (such as bandwidth limitation) multiple senders should be employed for reliable multimedia streaming. This paper introduces a mathematic approach to select a set of senders among all available senders to provide the most reliable stream for the receiver. This selection is based on upload bandwidths and availability of peers as well as bandwidth of links connecting the senders and the receiver. Our method is called IPROMISE as it is an improved version of the PROMISE algorithm. Simulation results demonstrate improved media quality delivered to the receiver, while the complexity of sender selection remains the same. © 2007 IEEE  

Unlike those on Internet, the media providers on P2P networks are ordinary nodes with limited shared resources such as bandwidth. Multi-sender methods are the best existing solutions to video streaming on P2P networks. In this paper, we propose use of a multicast method on the top of an arbitrary multi-sender method so that all requesting peers receive almost the same expected bit-rate. Experimental results, derived from implementation of the proposed algorithm on Pastry P2P network confirm our claim. Another advantage of our method over the existing methods is its scalability with the number of receivers. © 2007 Elsevier B.V. All rights reserved  

In this research, we present results of simulated annealing (SA), a heuristic optimization algorithm, for focusing light through a turbid medium. Performance of the algorithm on phase and amplitude modulations has been evaluated. A number of tips to tune the optimization parameters are provided. The effect of measurement noise on the performance of the SA algorithm is explored. Additionally, SA performance is compared with continuous sequential and briefly with other optimization algorithms. © 2018 Optical Society of America  

Secure routing is a major key to service maintenance in ad hoc networks. Ad hoc nature exposes the network to several types of node misbehavior or attacks. As a result of the resource limitations in such networks nodes may have a tendency to behave selfishly. Selfish behavior can have drastic impacts on network performance. We have proposed a Misbehavior-Tolerant Multipath Routing protocol (MTMR) which detects and punishes all types of misbehavior such as selfish behavior, wormhole, sinkhole and grey-hole attacks. The protocol utilizes a proactive approach to enforce cooperation. In addition, it uses a novel data redirection method to mitigate the impact of node misbehavior on network...