As a result of improvements in wireless communication technologies, a multimedia data streaming service can be provided for mobile clients such as PDAs and cellular phones. Because mobile devices have low computing po...
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ISBN:
(纸本)9781424459421;9781424459438
As a result of improvements in wireless communication technologies, a multimedia data streaming service can be provided for mobile clients such as PDAs and cellular phones. Because mobile devices have low computing power and work on a low network bandwidth, a transcoding technology is needed to adapt the original streaming media for mobile environments. To provide quality of service, original encoded media are transcoded within limited time and transmitted to clients without ceasing and jittering phenomena. In particular, when large-scale mobile clients demand streaming services, load distribution methods among distributed transcoding servers have a tremendous impact on the total number of quality of service streams. In this paper, a new load distribution method is proposed based on transcoding time estimation with transcoding servers' information, movie information and target transcoding bit-rate. In experiments, the proposed method produces the best performance scalability according to the increase of transcoding servers.
We study the asymptotic properties of distributed consensus algorithms over switching directed random networks. More specifically, we focus on consensus algorithms over independent and identically distributed, directe...
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ISBN:
(纸本)9781424477456
We study the asymptotic properties of distributed consensus algorithms over switching directed random networks. More specifically, we focus on consensus algorithms over independent and identically distributed, directed random graphs, where each agent can communicate with any other agent with some exogenously specified probability. While different aspects of consensus algorithms over random switching networks have been widely studied, a complete characterization of the distribution of the asymptotic value for general asymmetric random consensus algorithms remains an open problem. In this paper, we derive closed-form expressions for the mean and an upper bound for the variance of the asymptotic consensus value, when the underlying network evolves according to an i.i.d. directed random graph process.
Currently, performance analysis of multimedia-MPSoC platforms largely rely on simulation. The execution of one or more applications on such a platform is simulated for a library of test video clips. If all specified p...
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ISBN:
(纸本)9781605586281
Currently, performance analysis of multimedia-MPSoC platforms largely rely on simulation. The execution of one or more applications on such a platform is simulated for a library of test video clips. If all specified performance constraints are satisfied for this library, then the architecture is assumed to be well-designed. This is similar to testing software for functional correctness. However, in contrast to functional testing, simulating a set of video clips for a complex application/architecture is extremely time consuming. In this paper we propose a technique for clustering a library of video clips, such that it is sufficient to simulate only one clip from each cluster rather than the entire library. Our clustering is scalable, i.e., the number of clusters may be determined based on the number of clips that the system designer wishes to simulate (which is independent of the input library size). For each video clip in the library, we perform a fast bitstream analysis from which the workload generated while processing this clip on the given architecture may be estimated. This workload information, in conjunction with a workload model and a performance model of the architecture, is used for the clustering. This entire process does not involve any simulation and is hence extremely fast. We illustrate its utility through a detailed case study using an MPEG-2 decoder application running on an MPSoC platform. As part of validation of our methodology, it was observed that video clips falling into the same cluster exhibit similar worst case buffer backlogs and worst case delays for one macroblock. Overall the results demonstrate that the proposed method provides a very fast and accurate analysis and hence can be of significant benefit to the system designer. Copyright 2009 ACM.
Many real natural or man-made dynamic systems can be better characterized using a fractional order dynamic model. Since in such a case the order assumes a non-integer value, it is of interest to consider the effect of...
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Many real natural or man-made dynamic systems can be better characterized using a fractional order dynamic model. Since in such a case the order assumes a non-integer value, it is of interest to consider the effect of small perturbation around the nominal value. It is of practical importance to analyze the influence of the order variations on the system behavior. This paper establishes an analytical method for the analysis of the sensitivity function of LTI fractional order dynamic systems with respect to the orders. The continuous dependent condition of the orders of fractional Green's function is derived, which is proved as a necessary and sufficient condition. The singularity of fractional Green's functions is discussed. Several examples are included for illustration.
There are several applications for which it is important to both detect and communicate changes in data models. For instance, in some mobile robotics applications (e.g. surveillance) a robot needs to detect significan...
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There are several applications for which it is important to both detect and communicate changes in data models. For instance, in some mobile robotics applications (e.g. surveillance) a robot needs to detect significant changes in the environment (e.g. a layout change) which it may achieve by comparing current data provided by its sensors with previously acquired data (e.g. map) of the environment. This often constitutes an extremely challenging task due to the large amounts of data that must be compared in real-time. This paper proposes a framework to detect, and represent changes through a compact model. The main steps of the procedure are: multi-scale sampling to reduce the computation burden; change detection based on Gaussian mixture models; fitting superquadrics to detected changes; and refinement and optimization using the split and merge paradigm. Experimental results in various real and simulated scenarios demonstrate the approach's feasibility and robustness with large datasets.
The short time-to-market window for embedded systems demands automation of design methodologies for customizable processors. Recent research advances in this direction have mostly focused on single criteria optimizati...
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ISBN:
(纸本)9781605584973
The short time-to-market window for embedded systems demands automation of design methodologies for customizable processors. Recent research advances in this direction have mostly focused on single criteria optimization, e.g., optimizing performance though custom instructions under pre-defined area constraint. From the designer's perspective, however, it would be more interesting if the conflicting trade-offs among multiple objectives (e.g., performance versus area) are exposed enabling an informed decision making. Unfortunately, identifying the optimal trade-off points turns out to be computationally intractable. In this paper, we present a polynomial-time approximation algorithm to systematically evaluate the design trade-offs. In particular, we explore performance-area trade-offs in the context of multi-tasking real-time embedded applications to be implemented on a customizable processor. Copyright 2009 ACM.
This paper describes a nonlinear Image-Based Visual Servo (IBVS) controller for the Flare phase of the landing maneuver of a fixed-wing aircraft in the presence of wind gust. Optic-Flow and 2D image features are explo...
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ISBN:
(纸本)9781424477456
This paper describes a nonlinear Image-Based Visual Servo (IBVS) controller for the Flare phase of the landing maneuver of a fixed-wing aircraft in the presence of wind gust. Optic-Flow and 2D image features are exploited from the image of the runway to design a feedback controller for the automatic maneuver. The controller is divided into two parts. The first part guarantees the horizontal alignment with the center of the runway and uses the two lines delimiting the runway represented through a modification of the so-called Plucker coordinates. The second part takes advantage of the Optic-Flow measurements to ensure a smooth touchdown. Simulation results are presented to illustrate the performance of the control approach.
This paper addresses the problem of steering a quadrotor vehicle along a time-dependent trajectory. The problem is formulated so as to take into account force disturbances acting on the vehicle and enforce bounds on t...
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Echo State Network (ESN) is a new type of Recurrent Neural Network (RNN) proposed in recent years. The training process of ESN is easier and requires less computational effort than regular RNN which has the same size....
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Motor failures in aerospace applications can lead to serious compromises in safety, overall effectiveness, and maintenance costs. In mission critical applications, it is important that motor fault signatures are ident...
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