We report on our preliminary studies of a new controller for a two-link brachiating robot. Motivated by the pendulum-like motion of an ape's brachiation, we encode this task as the output of a "target dynamic...
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We report on our preliminary studies of a new controller for a two-link brachiating robot. Motivated by the pendulum-like motion of an ape's brachiation, we encode this task as the output of a "target dynamical system". Numerical simulations indicate that the resulting controller solves a number of brachiating problems that we term the "ladder", "swing up" and "rope" problems. Preliminary analysis provides some explanation for this success. We discuss a number of formal questions whose answers will be required to gain a full understanding of the strengths and weaknesses of this approach.
A continuous periodic time-varying feedback law is proposed that exponentially stabilizes both the position and orientation of a surface vessel having only two actuators. To this end, a stability result for a class of...
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A continuous periodic time-varying feedback law is proposed that exponentially stabilizes both the position and orientation of a surface vessel having only two actuators. To this end, a stability result for a class of homogeneous time-periodic systems is presented. The exponential stability provided by the proposed feedback law does not depend on exact knowledge of the model parameters, and is thus robust to model parameter uncertainty. The surface vessel model considered is nonlinear and describes both the dynamics and the kinematics of the surface vessel. Furthermore the actuator dynamics is included in the control design. simulation results are presented.
We present an approach to testing implementations of real-time and fault-tolerant protocols. In our object-oriented tool, implementations are subject to real interactions with the environment, and to the same failure ...
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We present an approach to testing implementations of real-time and fault-tolerant protocols. In our object-oriented tool, implementations are subject to real interactions with the environment, and to the same failure scenarios they are designed to tolerate. A centralized simulator executes all the tasks of the distributed system on a single address space. Testing is nonintrusive; the timing of events is exactly the same in real and simulated executions. Experiments can be exactly reproduced any number of times. Our tool helped us find several flaws in the implementation of a fault-tolerant clock synchronization protocol, and get detailed performance measurements that would have been extremely difficult to get in a real distributed system.
In this paper, we consider the mesh with a single bus as a multi-computer topology that enhances the communication capability of the mesh and show that the mesh with a single bus has more salient properties than the m...
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ISBN:
(纸本)0818682272
In this paper, we consider the mesh with a single bus as a multi-computer topology that enhances the communication capability of the mesh and show that the mesh with a single bus has more salient properties than the mesh, the hypercube, and other mesh variants. These properties are small diameter, relatively small degree, small average distance, suitable for broadcasting, small initial data distribution time, etc. We propose a dynamic load distribution algorithm to utilize the enhanced communication capability of the mesh with a single bus. Also, asynchronous bus control and arbitration logic is designed to support the proposed algorithm efficiently. It is shown through simulation that the proposed dynamic load distribution is superior to the previous receiver-initiated diffusion method known as the best to-date. The proposed algorithm shows better total execution time of tasks and better processor utilization with a smaller number of task migrations.
The authors propose to detect users' navigation paths to the advantage of Web site owners. First, they explain the design and implementation of a profiler which captures a client's selected links and page orde...
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The authors propose to detect users' navigation paths to the advantage of Web site owners. First, they explain the design and implementation of a profiler which captures a client's selected links and page order, accurate page viewing time and cache references, using a java based remote agent. The information captured by the profiler is then utilized by a knowledge discovery technique to cluster users with similar interests. They introduce a novel path clustering method based on the similarity of the history of user navigation. This approach is capable of capturing the interests of the user which could persist through several subsequent hypertext link selections. Finally, they evaluate their path clustering technique via a simulation study on a sample WWW site. They show that, depending on the level of inserted noise, they can recover the correct clusters by 10%-27% of average error margin.
Instruction cache prefetching is a technique to reduce the penalty caused by instruction cache misses. The prefetching methods generally determine the target line to be prefetched based on the current fetched line add...
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ISBN:
(纸本)0818682272
Instruction cache prefetching is a technique to reduce the penalty caused by instruction cache misses. The prefetching methods generally determine the target line to be prefetched based on the current fetched line address. However, as the cache line becomes wider, there may be multiple branches in a cache line which hurdles the decision made by these methods. This paper develops a new instruction cache prefetching method in which the prefetch is directed by the prediction on branches. We call it the branch instruction based (BIB) prefetching. In BIB prefetching, the prefetch information is recorded in an extended BTB. simulation results show that, the BIB prefetching outperforms the traditional sequential prefetching by 7% and other prediction table based prefetching methods by 17% on average. As the BTB designs become more sophisticated and achieve higher hit and accuracy ratio, the BIB prefetching can achieve higher performance.
Considering that the application of a direct-sequence slotted spread ALOHA communications system in the access/control channel is effective in systems with traffic channels operating in the CDMA mode, spread ALOHA com...
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Considering that the application of a direct-sequence slotted spread ALOHA communications system in the access/control channel is effective in systems with traffic channels operating in the CDMA mode, spread ALOHA communications is discussed in terms of the system configuration and throughput performance. The throughput performance of the spread ALOHA communications system using a unified spread code is derived by means of two methods. One is based on the simulation of the demodulation algorithm, and the other is based on an approximation by simple modeling. The modeling consists of two main conditions depending on the collision of packet signals. It becomes obvious from a quantitative evaluation that the approximated results coincide with the simulated results, and that the modeling is very effective in evaluating the system's throughput performance.
In order to set up international standards for medical infrared thermography the authors have been developing an international communication tool on the World Wide Web (WWW) named Biomedical Thermology Homepage (http:...
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In order to set up international standards for medical infrared thermography the authors have been developing an international communication tool on the World Wide Web (WWW) named Biomedical Thermology Homepage (http://***/bmth/). The methodology and system concept have been reported (I. Fujimasa et al., 1996). In this report, the concept and methodology of the image database named Gallery are reported. The keynotes are how one establishes remote access of image handling software to analyze common source binary images in the database. The authors have developed software which was written with Visual Basic and java. The system, which has included more than 20000 binary images, has been tested for its feasibleness from remote sites.
This paper studies the synthesis of quadratic control for a class of large-scale systems, which composed of N identical subsystems interconnected with an external system in a similar fashion. The similar structural in...
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ISBN:
(纸本)0780341872
This paper studies the synthesis of quadratic control for a class of large-scale systems, which composed of N identical subsystems interconnected with an external system in a similar fashion. The similar structural information is utilized to reduce the synthesis of control design to solving several low order algebraic Riccati inequalities determined by corresponding isolated subsystems and the similar structural information of interconnections. A simulation example is included to demonstrate the effectiveness of the presented methods.
Efficient routing of traffic in any sort of network is obviously dependent on the topology of the network and the volume, distribution and mix of traffic. The paper considers the likely topology of future ATM networks...
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Efficient routing of traffic in any sort of network is obviously dependent on the topology of the network and the volume, distribution and mix of traffic. The paper considers the likely topology of future ATM networks and the mix of traffic that they will carry. It proposes an arrangement which can be used, when simulating ATM network routing algorithms. The particular interest is in the routing overhead of flooded status information which is used to calculate or discover optimal routes. The experimental topology used in the study is a flat, sparsely connected mesh of 43 nodes based on a segment of the BT network to the south and east of London. Since the network exists and serves a "real" user community, it is possible to make reasoned estimates of the magnitude and mix of the offered load using population and behavioural statistics. Three different traffic scenarios are considered. These are telephone, audio-visual and data traffic and each traffic class are carried in a separate overlay (virtual path) network which supports the appropriate quality of service. simulation is used to predict the variation in the pattern and volume of traffic, and subsequently the generation of routing status update messages.
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