There has recently been increasing interests in using system virtualization to improve the dependability of HPC cluster systems. However, it is not cost-free and may come with some performance degradation, uncertain Q...
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Given that state of the art speech synthesis systems have already reached a high naturalness level, it is time to move to talking speech from the actual read speech framework. For this purpose it is thus necessary to ...
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Voice over IP technology enabled the growth of Internet telephony applications that make use of public common infrastructures to provide voice and data communications to their users. The growth of wireless Internet en...
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ISBN:
(纸本)9789630626705
Voice over IP technology enabled the growth of Internet telephony applications that make use of public common infrastructures to provide voice and data communications to their users. The growth of wireless Internet enables users to connect to the network from different locations using mobile Internet devices. Security is a major concern for mobile Internet telephony users, yet the lack of secure inline key exchange mechanisms is one of the major drawbacks for the use of these applications for business use. The intrinsic vulnerabilities of wireless networks make the VoWiFI case even worse while compromising security of a call is as easy as breaching human administration security of the service network. In this paper we describe the design and implementation of a secure VoIP application for handheld devices that is using the strong security mechanisms of Voice Interactive Personalized Security protocol (VIPSec). We analyze the architectural fundamentals and we present the implementation elements of the application. User sign-in and other subsidiary procedures follow the Client-Server model while the media path is direct between the users. The application is developed in Java and is suitable for mobile devices running Windows CE or Linux, essentially securing end-to-end voice, video and data communications in wireless communications. Copyright 2007 ICST.
In this paper we give an overview of recent results on the rate maximization game in the Gaussian frequency-selective interference channel. We focus on the competitive maximization of information rates, subject to glo...
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ISBN:
(纸本)9780615153148
In this paper we give an overview of recent results on the rate maximization game in the Gaussian frequency-selective interference channel. We focus on the competitive maximization of information rates, subject to global power and spectral mask constraints. To achieve the so-called Nash equilibrium points of the game Yu, Ginis and Cioffl proposed the sequential Iterative Waterfilling Algorithm (IWFA), where, at each iteration, the users choose, one after the other, their power allocation to maximize their own information rate, treating the interference generated by the others as additive colored Gaussian noise. To overcome the potential slow convergence of the sequential update, specially when the number of users is large, the simultaneous IWFA was proposed by the authors, where, at each iteration, all the users update their power allocations simultaneously, rather than sequentially. Recently, the authors showed that both the sequential and the simultaneous IWFAs are just special cases of a more general unified framework, given by the totally asynchronous IWFA. In this more general algorithm, the users update their power spectral density in a completely distributed and asynchronous way. Furthermore, the asynchronous setup includes another form of lack of synchronism where the transmission by the different users contains time and frequency synchronization offsets. A unified set of convergence conditions were provided for the whole class of algorithms obtained from the asynchronous IWFA. Interestingly, there is a key result used in the proof of convergence of the algorithms: an alternative interpretation of the waterfilling operator as a projector.
This paper considers the competitive maximization of information rates in the Gaussian frequency-selective interference channel, subject to global power and spectral mask constraints. We focus on the practical case in...
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Because the notion of context is multi-disciplinary [17], it encompasses lots of issues in Information Retrieval. In this paper, we define the context as the information surrounding one document that is conveyed via t...
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Because the notion of context is multi-disciplinary [17], it encompasses lots of issues in Information Retrieval. In this paper, we define the context as the information surrounding one document that is conveyed via the hypertext links. We propose different measures depending on the information chosen to enrich a current document, in order to assess the impact of the contextual information on hypertext documents. Experiments were made over the TREC-9 collections and significant improvement of the precision shows the importance of taking account of the contextual information.
We propose an online resource allocation solution for multiprocessor systems-on-chip, that executes several real-time, streaming media jobs simultaneously. The system consists of up to 24 processors connected by an -t...
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ISBN:
(纸本)1595934804;9781595934802
We propose an online resource allocation solution for multiprocessor systems-on-chip, that executes several real-time, streaming media jobs simultaneously. The system consists of up to 24 processors connected by an -thereal [7] Network-on-Chip (NoC) of 4 to 12 routers. A job is a set of processing tasks connected by FIFO channels. Each job can be independently started or stopped by the user. Each job is annotated with resource budgets per computation task and communication channel which have been computed at compile-time. When a job is requested to start, resources that meet the required resource budgets have to be found. Because it is done online, allocation must be done with low-complexity algorithms. We do the allocation in two-steps. First, tasks are assigned to virtual tiles (VTs), while trying to minimise the total number of VTs and the total bandwidth used. In the second step, these VTs are mapped to real tiles, and network bandwidth allocation and routing are performed simultaneously. We show with simulations that introducing randomisation in the processing order yields a signicant improvement in the percentage of mapping succdesses. In combination these techniques allow 95% of the processor resources to be allocated while handling a large number of job arrivals and departures. Copyright 2007 ACM.
We use χ2 to investigate the context dependency of student affect in our computer tutoring dialogues, targeting uncertainty in student answers in 3 automatically monitorable contexts. Our results show significant dep...
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This paper presents a new approach to the problem of simultaneous location and segmentation of object in images. The main emphasis is done on the information provided by the contour fragments present in the image. Clu...
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