16819932
A Client Peer Adjustment Policy for Peer-to-Peer Media Streaming
Previous work indicates that more cooperation is needed between peers for peer-to-peer (P2P) media streaming application than files sharing. That implies it is important to select cooperators in P2P networks. However, most of peer selection algorithms are performed at requesting ones and focus on how to choose servers from which clients can benefit more while ignoring whether the scalability and service capacity of systems will be influenced by these results. In this paper, we pay more attention to heterogeneous network capacity of peers and propose a policy fulfilled by server peers to select and adjust clients according to their service capacity and contribution. Peers with higher service capacity may replace existing children. And experiments proved that our policy could improve system's overall utilization and contribution, as well as the depth of multicast tree when compared with delay-based algorithm
37799288
On Building and Updating Distributed LSI for P2P Systems
Recently published studies have shown that Latent Semantic Indexing (LSI) plays an important role in content-based full text information retrieval of P2P system. However, it is a challenging problem to generate global consistent LSI structures in P2P systems because their nodes are self-organizing and their corpora are large, dynamic and distributed on different nodes. In this paper we propose a method for building LSI structures from distributed corpora. Our method is consisted with a network model for semantic information sampling and exchanging and a Reduced-Dimension-Representation (RDR)s merging algorithm. By the signal and noise subspace model, we also provide a theoretical justification that the RDR merging algorithm is sound. A simple numerical experiment shows that our RDR merging algorithm can keep query precision on an acceptable level.
29357540
Multi-feature Fusion Method of Driver Face Location Based on Area Coincidence Degree and Prior Knowledge
Speedy and reliable face location is a key for monitoring driver fatigue driving condition using machine vision methods. According to the disadvantage of face location methods based on single feature in accuracy and reliability at present, first, an improved face location method based on Haar-like feature and Adaboost is used to detect the possibly existing face region in the whole image, then the detected region is extended properly and a face location method based on skin color feature in normalized rgb and HSV color spaces is used to locate the face again in the extended area, finally, fusion location of driver face region is achieved by the defined area coincidence degree and prior knowledge of human face. Experiments carried out in various road environments demonstrate the validity of the fusion method proposed.
19886214
Robust and Adaptive Backstepping Control for Nonlinear Systems Using Fuzzy Logic Systems
In this note, a robust adaptive tracking control problem is discussed for a class of affine nonlinear systems in the strict-feedback form with unknown nonlinearities. A unified and systematic procedure is developed to derive a novel robust adaptive fuzzy controller. Compared with most results reported in the literature, the proposed control algorithm has several advantages: 1) the controller singularity problem is avoided perfectly; 2) the online computation burden is kept to minimum; 3) exponential tracking to the reference trajectory up to an ultimately bounded error is achieved; 4) the controllers are particularly suitable for parallel processing and hardware implementation.
1848954
Adaptive Indexing of Moving Objects with Highly Variable Update Frequencies
In recent years, management of moving objects has emerged as an active topic of spatial access methods. Various data structures (indexes) have been proposed to handle queries of moving points, for example, the well-known Bx-tree uses a novel mapping mechanism to reduce the index update costs. However, almost all the existing indexes for predictive queries are not applicable in certain circumstances when the update frequencies of moving objects become highly variable and when the system needs to balance the performance of updates and queries. In this paper, we introduce two kinds of novel indexes, named By-tree and αBy-tree. By associating a prediction life period with every moving object, the proposed indexes are applicable in the environments with highly variable update frequencies. In addition, the αBy-tree can balance the performance of updates and queries depending on a balance parameter. Experimental results show that the By-tree and αBy-tree outperform the Bx-tree in various conditions.
33357953
PISA: Federated Search in P2P Networks with Uncooperative Peers
Recently, federated search in P2P networks has received much attention. Most of the previous work assumed a cooperative environment where each peer can actively participate in information publishing and distributed document indexing. However, little work has addressed the problem of incorporating uncooperative peers, which do not publish their own corpus statistics, into a network. This paper presents a P2P-based federated search framework called PISA which incorporates uncooperative peers as well as the normal ones. In order to address the indexing needs for uncooperative peers, we propose a novel heuristic query-based sampling approach which can obtain high-quality resource descriptions from uncooperative peers at relatively low communication cost. We also propose an effective method called RISE to merge the results returned by uncooperative peers. Our experimental results indicate that PISA can provide quality search results, while utilizing the uncooperative peers at a low cost.
11514235
Nonequilibrium electron and phonon transport and energy conversion in heterostructures
Abstract We establish a unified model dealing with the transport of electrons and phonons in double heterojunction structures with the coexistence of three nonequilibrium processes: (1) nonequilibrium among electrons, (2) nonequilibrium among phonons, and (3) nonequilibrium between electrons and phonons. Using this model, we investigate the energy conversion efficiency based on concurrent thermoelectric and thermionic effects on electrons and size effects on electrons and phonons. It is found that heterostructures can have an equivalent figure of merit higher than the corresponding bulk materials.
17872919
Extremal search of decision policies for scalable distributed applications
The ongoing trend of constructing open, scalable distributed systems such as peer-to-peer (P2P) systems demands for effective tools to manage the interactions between constituent entities (or nodes). One such tool is through imposing decision policies at the network level. However very few techniques are available to allow computers autonomously identify good policies with limited human intervention. In this paper, we propose an Extremal Programming (EP) algorithm to achieve automatic policy identification. The algorithm is inspired by recent advances in understanding far from equilibrium phenomena in terms of self-organized criticality (SOC). The effectiveness of EP is evaluated through a P2P application called location-aware video streaming (LAVS). The simulation studies in LAVS demonstrate that with EP, the fast and effective sharing of video streams is achieved.