Rate-based congestion control is effective and still simple for traffic management in ATM networks. One of its practical realization schemes is the enhanced proportional rate control algorithm (EPRCA) which has been p...
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ISBN:
(纸本)0780325109
Rate-based congestion control is effective and still simple for traffic management in ATM networks. One of its practical realization schemes is the enhanced proportional rate control algorithm (EPRCA) which has been proposed and adopted as a standard for traffic management scheme in the ATM Forum. An analysis for the EPRCA is provided for a network with homogeneous source traffic and a single bottleneck ATM link to investigate the dynamic behavior of the EPRCA. In addition to three types of switches suggested in the EPRCA, a prioritized switch is newly proposed. We exploit the dynamical behavior of the EPRCA and obtain the maximum queue length at the switch and the throughput by using the first-order fluid approximation method. Equations for parameter tuning for the EPRCA are also provided.
We describe a method of object-selective quantizer control in a standard coding system based on MC DCT-CCITT Recommendation H.261. The approach is based on two novel algorithms, namely buffer rate modulation and buffe...
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ISBN:
(纸本)0780331222
We describe a method of object-selective quantizer control in a standard coding system based on MC DCT-CCITT Recommendation H.261. The approach is based on two novel algorithms, namely buffer rate modulation and buffer size modulation. By forcing the rate control algorithm to transfer a relatively small fraction-about 10-15% on average-of the total available bit rate from the coding of the non-facial to that of the facial area, in head-and-shoulders videoteleconferencing sequences, images with better-rendered facial features are obtained, i.e. blocky artifacts in the facial area are less pronounced and eye contact and lip-sync are preserved. The improvement was found to be perceptually significant on video sequences coded at the rate of 64 kbps, with 48 kbps allocated for the input (color) video signal in QCIF format.
A method of synthesizing a control system comprising a most inner positive voltage feedback loop and an inner negative voltage feedback loop and an outer negative voltage feedback loop is presented. The control system...
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A method of synthesizing a control system comprising a most inner positive voltage feedback loop and an inner negative voltage feedback loop and an outer negative voltage feedback loop is presented. The control system error is forced to zero in steady state and minimized in transient in response to either input command change or external disturbance. No current through the plant under the control is sensed and no parameters of the plant are required to be known implying minimization of measurement noise and adaptive/self-tuning operation, respectively. The method is used to synthesize load-independent and input-voltage-independent switch-mode power converters as well as electric motor drive systems, incorporating any kind of electric motor, of maximized disturbance rejection ratio and minimized dynamics.
Symbolic languages are increasingly being used in the analysis and implementation of control algorithms. Many of these control procedures involve some type of differentiation or Jacobian formulation. Automatic differe...
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Symbolic languages are increasingly being used in the analysis and implementation of control algorithms. Many of these control procedures involve some type of differentiation or Jacobian formulation. Automatic differentiation provides an alternative means of computing this information which is rarely considered in the control literature. This correspondence will discuss the use of automatic differentiation. Numerical results comparing the use of automatic differentiation and symbolic approaches in the context of a particular nonlinear control system will be given.
A method to transmit multiplexed digital video that potentially allows for video quality and capacity gains over conventional constant bit-rate (CBR) transmission is described. The method uses a joint rate control alg...
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A method to transmit multiplexed digital video that potentially allows for video quality and capacity gains over conventional constant bit-rate (CBR) transmission is described. The method uses a joint rate control algorithm that regulates the encoders during buffer congestion periods using bandwidth re-allocation and source rate control. A multichannel joint rate control algorithm is described and its performance simulated for MPEG encoded video on a typical Direct Broadcast Satellite (DBS) indicate significant capacity and/or quality gains conventional CBR transmission methods.
As the deployment of high-speed fiber transmission systems has been accelerated, they are widely recognized as a firm infrastructure of our information society. Under this circumstance, the importance of network survi...
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As the deployment of high-speed fiber transmission systems has been accelerated, they are widely recognized as a firm infrastructure of our information society. Under this circumstance, the importance of network survivability has been increasing rapidly in these days. In SONET, the self-healing networks have been highlighted as one of the most advanced mechanisms to realize SONET survivable networks. Several schemes have been proposed and studied actively due to a rapid progress on the development of highly intelligent NE's. Among them in this paper, a DCS based distributed self-healing network is discussed from a viewpoint of its control algorithms. Specifically, our self-healing algorithm called TRANS is explained in detail, which possesses such desirable features as providing fast and flexible restoration with line and path level restoration applied to an individual STS-1 channel, capability to handle multiple and even node failures, and so on. Both software simulation and hardware experiment verify that TRANS works properly in a real distributed environment, the result of which is shown in the paper. In addition, the combined use of TRANS and the ring restoration control is proposed taking into account the use in a practical SONET.
Based on a unified analysis of both pure and slotted ALOHA systems, a new control algorithm for ALOHA systems is proposed. A feature of great practical importance is the algorithm's automatic adjustment to changes...
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Based on a unified analysis of both pure and slotted ALOHA systems, a new control algorithm for ALOHA systems is proposed. A feature of great practical importance is the algorithm's automatic adjustment to changes in average traffic intensity or the (finite or infinite) number of active stations in the system. In addition, the algorithm has a low-complexity implementation. computer simulations, concentrating on the use for two-way data communication in a cable television network, have demonstrated that the practical performance of the algorithm closely approximates the theoretical optimum, even under extremely heavy traffic load conditions. Furthermore, dynamic performance simulations have shown that the algorithm assures swift recovery from overload situations.
The development and performance of moving-bank multiple model adaptive control (MMAC) algorithms for quelling vibrations induced in the SPICE 2 space structure are presented. The structure consists of a large platform...
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The development and performance of moving-bank multiple model adaptive control (MMAC) algorithms for quelling vibrations induced in the SPICE 2 space structure are presented. The structure consists of a large platform and a smaller platform connected by three legs in a tripod fashion. Deviations of the line-of-sight (LOS) vector from the center of the large platform to the center of the smaller platform are used for LQG controller performance evaluation. The parameter estimator implements the maximum entropy with identity covariance (ME/I) algorithm;the moving bank logic employs parameter position monitoring the controller uses the modified MMAC method. Whereas parameter variations of two percent caused instabilities in the single filter/controller design, the MMAC algorithm provides an excellent method to estimate a wide range of parameter variations and to quell oscillations in the structure.
Two algorithms for the complete automation of background estimation in ICP emission spectroscopy are presented and evaluated. One of these algorithms is based on heuristic spectral interpretation, while the other is b...
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Two algorithms for the complete automation of background estimation in ICP emission spectroscopy are presented and evaluated. One of these algorithms is based on heuristic spectral interpretation, while the other is based on statistical spectral interpretation. These algorithms both address the weaknesses of the conventionally employed approaches of blank subtraction in calibration and background estimation through interpolation from analyst-selected wavelengths adjacent to the analyte peak. In a rigorous evaluation with synthetic spectra, these algorithms are characterized for performance in terms of accuracy, precision, and robustness. As a demonstration of the algorithms' performance with experimentally measured spectra, a determination of uranium in the presence of a calcium background interference is performed. These algorithms require no analyst interaction for their operation, and they estimate the background for every spectrum measured.
We suggest a new approach to the derivation of programs from their specifications. The formal derivation and proof of programs as is practiced today is a very powerful tool for the development of high-quality software...
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We suggest a new approach to the derivation of programs from their specifications. The formal derivation and proof of programs as is practiced today is a very powerful tool for the development of high-quality software. However, its application by the software development community has been slowed by the amount of mathematical expertise needed to apply these formal methods to complex projects and by the lack of reuse within the framework of program derivation. To address these problems, we have developed an approach to formal derivation that employs the new concept of generic algorithms. A generic algorithm is one that has (1) a formal specification, (2) a proof that it satisfies this specification, and (3) generic identifiers representing types and operations. It may have embedded program specifications or pseudocode instructions describing the next steps in the stepwise refinement process. Using generic algorithms, most software developers need to know only how to pick and adapt them, rather than perform more technically challenging tasks such as finding loop invariants and deriving loop programs. The adaptation consists of replacing the generic identifiers by concrete types and operations. Since each generic algorithm can be used in the derivation of many different programs, this new methodology provides the developer with a form of reuse of program derivation techniques, correctness proofs, and formal specifications.
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