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A packet selection algorithm for adaptive transmission of smoothed video over a wireless channel

JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING 2000年第4期60卷 494-509页

作者： Jiang, ZM Kleinrock, L AT&T Labs Res Murray Hill NJ 07974 USA Univ Calif Los Angeles Dept Comp Sci Los Angeles CA 90024 USA

This paper discusses techniques for transmitting smoothed video more efficiently over a wireless network. The fluctuation of wireless channel conditions can add a significant amount of delay to video packets and cause them to miss their play-out time. If a video is smoothed, it is possible to selectively deliver packets delayed at the base-station to reduce the impact of the missing packets on video quality. In this paper, we present a simple yet effective packet selection algorithm which accomplishes this goal. This algorithm determines whether to transmit a packet based on channel conditions as well as the likelihood that higher priority layers in the rest of the video will be delivered on time. We introduce the concept of quality index to measure the performance of the algorithm. Results from trace-driven simulations show that the performance of the algorithm is close to optimal under a wide variety of channel conditions when the threshold is set between 0.7 and 0.9. (C) 2000 Academic Press.

关键词： Adaptive transmission BASE STATION Packet quality indicator Videotapes selection algorithm Wireless networks wireless wireless channels smoothing

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Flexibility and the use of indicator taxa in the selection of sites for nature reserves

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BIODIVERSITY AND CONSERVATION 2001年第2期10卷 271-285页

作者： Hopkinson, P Travis, JMJ Evans, J Gregory, RD Telfer, MG Williams, PH Univ London Imperial Coll Sci Technol & Med NERC Ctr Populat Biol Ascot SL5 7PY Berks England NERC Ctr Ecol & Hydrol Biol Records Ctr Huntingdon PE17 2LS England Univ London Imperial Coll Sci Technol & Med Dept Biol Ascot SL5 7PY Berks England

'Minimum' sets of complementary areas represent all species in a region a given number of times. In recent years, conservation assessments have centred around the the evaluation of these 'minimum' sets. Previous research shows little overlap between minimum' sets and existing nature reserves and between 'minimum' sets Cur different taxonomic groups. The latter has been used as an argument to discount the use of indicator taxa in the selection of sites for nature reserves. However, these 'minimum' set analyses have only considered a single set for each taxonomic group when there are, in fact. a large number of equally valid 'minimum' sets. We present new methods for evaluating all of these alternative 'minimum' sets. Wt demonstrate that if all of the sets are evaluated, significantly higher levels of overlap are found between 'minimum' sets and nature reserves, and pairs of 'minimum' sets for different taxonomic groups. Furthermore, significantly higher proportions of species from non-target taxonomic groups are recorded in the 'minimum' sets of target Stoups Our results suggest that previous conservation assessments using 'minimum' sets may have been unduly pessimistic.

关键词： biodiversity near-minimum sets priorities protected areas selection algorithm

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Improved contingency selection algorithm for voltage security analysis

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ELECTRIC MACHINES AND POWER SYSTEMS 1998年第8期26卷 855-871页

作者： Singh, SN Srivastava, SC Univ Roorkee Dept Elect Engn Roorkee 247667 Uttar Pradesh India

A simple and efficient method for optimal selection of weights, along with higher order performance indices for voltage contingency selection, has been suggested in this ***. Some of the existing performance indices for voltage contingency selection has been critically reviewed. The proposed performance indices are able to eliminate misranking and masking effects. The post-outage quantities have been computed, using a new set of distribution factors, defned in terms of pre-outage real and reactive power flows in transmission lines/ outputs of generators. The proposed algorithm has been tested on IEEE 14-bus system and a practical 75-bus Indian system.

关键词： performance indicators contingency optimal selection voltage security distribution factor selection algorithm

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Segment pre-selection in decision-tree based speech synthesis systems 25

Segment pre-selection in decision-tree based speech synthesi...

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IEEE International Conference on Acoustics, Speech, and Signal Processing

作者： Donovan, RE IBM Corp TJ Watson Res Ctr Yorktown Hts NY 10598 USA

ISBN: (纸本)0780362934

Corpus based approaches to unit selection for concatenative speech synthesis have become popular in recent years due to their improved sensitivity to unit context over their more simple predecessors. These systems usually make use of large speech databases and employ sophisticated search algorithms to determine the optimal unit sequence to use to synthesise each sentence. For many applications it is not possible to have the entire database, which may be as large as several hundred megabytes. available to the synthesiser at runtime. What is required is some form of off-line pre-selection algorithm to determine which subset of the database enables the highest quality speech synthesis to be performed for a given runtime system size. This paper describes a pre-selection algorithm developed at IBM for use with decision-tree-based concatenative speech synthesisers.

关键词： Speech synthesis Primary election Decision Trees Runtime selection algorithm Database SEARCHING algorithm

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Action selection algorithms for autonomous microspacecraft

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1999年第6期22卷 914-916页

作者： Gillies, EA Johnston, AGY McInnes, CR Univ Glasgow Dept Aerosp Engn Glasgow G12 8QQ Lanark Scotland

A scheme for sequencing of tasks on a microspacecraft platform is outlined. The scheme is easily implemented by virtue of its computational simplicity. The strategy is derived from optimal control theory. Action selection with the cue-deficit algorithm is found to perform well on the present microsatellite simulation and to be demonstrably robust to significant failures of the satellite solar array. Robustness to failures of payload, transmitters, and injection into nonoptimum orbits, such as elliptical transfer orbits, rather than the mission orbit, is also demonstrated. (AIAA)

关键词： selection algorithm Satellites Ground Station Optimal Control Earth Attitude Control Depth of Discharge Elliptical Transfer Orbit Reaction Wheels Data Store

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Evaluation of an actuator placement method for active noise control applications

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JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME 1998年第4期120卷 875-879页

作者： Naghshineh, K Heck, LP Olkin, JA Kamman, JW Western Michigan Univ Dept Mech & Aeronaut Engn Kalamazoo MI 49008 USA

In our previous work, we developed a new actuator placement algorithm that is capable of selecting the best actuator placement for active noise control problems over a broad band of frequencies. The actuator selection algorithm is based on a novel extension of the Householder QR subset selection algorithm. The QR algorithm uses the l(2) matrix norm as a performance measure. In this paper, numerical results generated by that algorithm are compared with numerical results generated using five different performance measures. These measures, which are based on different matrix norms and functions of the actuator frequency responses, yield actuator placements that result in active noise control systems with improved performance and robustness.

关键词： Actuators Noise control Frequency response Robustness selection algorithm algorithms

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Design of deep stall protection for the C-17A

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1997年第4期20卷 760-767页

作者： Iloputaife, OI McDonnell Douglas Aerospace Long Beach California 90807-4418

The design of the C-17 angle-of-attack limiter system is presented. The C-17, because of its T-tail, has a locked-in deep stall potential in some aft center of gravity configurations. The angle of-attack system uses alpha measurements from three pairs of vanes for precise angle-of-attack control and to prevent excursion into the deep stall region. The vanes, because of their locations, are sensitive to sideslip angle excursions in varying degrees, therefore, requiring sideslip angle information for proper failure monitoring. A method of synthesizing sideslip and angle of attack using the information from the vanes was developed. With the synthesized angle of attack and sideslip, it was possible to provide a minimum of fail-operational-fail-operational capability with tight failure tolerance, After over 2000 stall tests and assaults to alpha limit, the pilot community has gained the confidence that the system will protect the C-17 from entering the locked in deep stall region.

关键词： Angle of Attack Sideslip Angle Air Vehicle Test Pilots Stick Pusher Pitching Moment Aircraft Roll Calibrated Airspeed Elevator selection algorithm

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selection on k-dimensional meshes with multiple broadcasting

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COMPUTER JOURNAL 1996年第2期39卷 140-144页

作者： Pan, Y Hamdi, M Singh, G HONG KONG UNIV SCI & TECHNOL DEPT COMP SCIKOWLOONHONG KONG KANSAS STATE UNIV DEPT COMP & INFORMAT SCIMANHATTANKS 66506

Randomized selection algorithms on k-dimensional mesh-connected computers with multiple broadcasting are proposed in this paper. We first show that a leader can be elected in O(log N) time on any k-dimensional mesh-connected computers with multiple broadcasting of size N. We then shaw that we can find the p-ah smallest element among a data set of size N in O((log N+k+N-1/(k(k+1)) log N) expected time using a regular N-1/k x...x N-1/k k-dimensional mesh and in O((log N+k(2)N(1/(k2k))) log N) expected time rasing an irregular N-(2k-1k+1/(k2k))x N-(2k-2k+1/(k2k)) x...x N-(k+1/(k2k)) dimensional mesh, This leads to a selection algorithm, which runs In O((log N)(2)) expected time on a regular ((log N/log log N)(1/2)))-dimensional mesh ai on an irregular (log log N)-dimensional mesh each with N processors. To our best knowledge, this is the first polylogarithmic selection algorithm on meshes with multiple broadcasting.

关键词： algorithm broadcasting algorithms Computers selection algorithm Medical Subject Headings

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Perpetuities with thin tails

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ADVANCES IN APPLIED PROBABILITY 1996年第2期28卷 463-480页

作者： Goldie, CM Grubel, R UNIV HANNOVER INST MATH STOCHAST D-30060 HANNOVER GERMANY UNIV LONDON QUEEN MARY & WESTFIELD COLL LONDON E1 4NS ENGLAND

We investigate the behaviour of P(R greater than or equal to r) and P(R less than or equal to-r) as r-->infinity for the random variable R:=Sigma(n=1)(infinity) Q(n) Pi(k=1)(n=1) M(k), where ((Q(k), M(k)))(k is an element of N) is an independent, identically distributed sequence with P(-1 less than or equal to M less than or equal to 1)=1. Random variables of this type appear in insurance mathematics, as solutions of stochastic difference equations, in the analysis of probabilistic algorithms and elsewhere. Exponential and Poissonian tail behaviour can arise.

关键词： perpetuity random affine map selection algorithm stochastic difference equation stochastic discounting tail behaviour

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MINIMUM-TIME REORIENTATION OF A 2-DEGREE-OF-FREEDOM GYROSCOPE

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1995年第4期18卷 782-791页

作者： BOYARSKI, S BENASHER, JZ Tel-Aviv University Ramat Aviv 69978 Israel

The problem of time-optimal reorientation of the inner gimbal of a two-degree-of-freedom gimballed gyroscope mounted on a nonrotating base is considered. The states in the gyro model are the gimbals' angles (nutation is ignored). The model is nonlinear (not limited to small angles), state constrained, control limited, and double input, double output. A simple, explicit solution based on an intuitive observation is presented;it exploits the system's nonlinearity and channel coupling for attaining the minimum-time goal,It is analytically shown, in detail, that the solution satisfies the Maximum Principle and fulfills a sufficient condition for optimality based on the Hamilton-Jacobi-Bellman equation.

关键词： Gyroscopes Degrees of Freedom Hamilton Jacobi Bellman Equation Closed Loop Control Moment Gyroscope Computing Actuator Torque Flexible Spacecrafts selection algorithm Real Time Software

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