Some of the previously proposed join operation implementations in several database machines are briefly analyzed. An associative parallel join module and its O(n) associative parallel algorithm are proposed. A VLSI ch...
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Some of the previously proposed join operation implementations in several database machines are briefly analyzed. An associative parallel join module and its O(n) associative parallel algorithm are proposed. A VLSI chip that has been simulated and fabricated is described, demonstrating the feasibility of the module.< >
Some of the fault-tolerance schemes that have been established as promising ones for use in real-time distributed computer systems (DCSs) are reviewed. Major issues that remain to be resolved in the 1990s are also dis...
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Some of the fault-tolerance schemes that have been established as promising ones for use in real-time distributed computer systems (DCSs) are reviewed. Major issues that remain to be resolved in the 1990s are also discussed. By and large, the design of fault-tolerant real-time DCSs is an immature field. Many of the promising fault tolerance schemes have not been adequately evaluated. It is hoped that many more testbed-based efforts will be made in the field of fault-tolerant real-time distributed computing.< >
The authors previously proposed (1984) the basic concept of the distributed recovery block (DRB) scheme as an approach to uniform treatment of hardware and software faults in real-time applications. Design issues that...
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The authors previously proposed (1984) the basic concept of the distributed recovery block (DRB) scheme as an approach to uniform treatment of hardware and software faults in real-time applications. Design issues that arise in implementing the DRB scheme are discussed together with some promising approaches. Issues in extending the DRB scheme with the capability of reincorporating a repaired node without disrupting the real-time computing service are also discussed. An experimental implementation of the repairable DRB scheme into a real-time distributed computer system (DCS) testbed and subsequent measurement of the system performance demonstrated the fast forward recovery capability and the logical soundness of the scheme.< >
Presents a quadtree communication structure and two associated procedures for efficient, contention-free data searching and distribution on the BBN Butterfly parallel processor and its family. The proposed quadtree st...
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Presents a quadtree communication structure and two associated procedures for efficient, contention-free data searching and distribution on the BBN Butterfly parallel processor and its family. The proposed quadtree structure suggests a general approach to mapping a class of parallel algorithms with intensive communication requirements for performing two primitive operations: selecting data from many different sources and distributing data from a single source. While performing these two operations through the quadtree structure, the 'ascend' and 'descend' procedures incur no link conflicts in the Butterfly network. A concrete example of mapping the linear programming algorithm is given to show the effectiveness of the proposed quadtree communication structure.< >
The impact of built-in self-test (BIST) techniques and system maintenance strategies on the performance of a VLSI processor system is examined. The specific BIST technique used was shown to have a significant influenc...
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The impact of built-in self-test (BIST) techniques and system maintenance strategies on the performance of a VLSI processor system is examined. The specific BIST technique used was shown to have a significant influence upon instantaneous and cumulative system reward. It was shown that the additional overhead of the distributed and BILBO approaches is justified for this model when area utilization and cumulative area utilization are considered. For the assumed design parameters, the results presented allow a VLSI system designer to choose an optimal configuration based on system requirements and individual component parameters. The optimal performance will also depend on system and component parameters such as processor failure rates and fault coverage. These results are relevant to the design, evaluation, and optimization of highly reliable, high-performance digital processing systems.< >
The extension of the transaction concept to the distributed environment has introduced problems not present in centralized systems. Some of these new problems are due to the communication network, which has become the...
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The extension of the transaction concept to the distributed environment has introduced problems not present in centralized systems. Some of these new problems are due to the communication network, which has become the major speed limitation factor. This suggests that minimizing communication in distributed transactions is as crucial as minimizing disk access for centralized systems. A system for distributed transaction processing that reflects this concern is presented. A novel construct called 'execute' is used that allows the initiation and execution of a group of remote operations with one command.< >
A high-speed fault simulator is presented that combines demand-driven simulation techniques with a bit-encoded deductive fault simulation scheme. The simulator uses an efficient approach to the management of signal va...
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A high-speed fault simulator is presented that combines demand-driven simulation techniques with a bit-encoded deductive fault simulation scheme. The simulator uses an efficient approach to the management of signal value and fault list structures intended to minimize disk thrashing during execution. Input cone analysis is used during preprocessing to identify gates with independent inputs so that optimized evaluation routines that include early cutoff can be used. Results are given for the demand-driven deductive fault simulator and contrasted with an earlier demand-driven parallel fault simulator.< >
Transesophageal atrial pacing (TAP) has been proposed as a noninvasive alternate modality of cardiac stress for patients who cannot perform an adequate exercise stress test. Present computer methods for processing the...
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Transesophageal atrial pacing (TAP) has been proposed as a noninvasive alternate modality of cardiac stress for patients who cannot perform an adequate exercise stress test. Present computer methods for processing the exercise ECG are inadequate in analyzing the unique surface ECG recorded during a TAP stress procedure. This is due to the presence of large simulator-induced pacing artifacts which confound computer beat identification. The authors have developed hardware to suppress the large pacing artifact, and a software method to detect the R wave, determine sustained capture, and calculate beat-by-beat and average ST-segment level, St slope, R-wave amplitude, and instantaneous RR interval and heart rate. They employ five different computer methods (single-point, average, weighted-average, linear least-squares and parabolic least-squares) in ST-segment measurements. They demonstrate the deficiency of present exercise ECG computer methods in processing the ECG during stress and show the significantly enhanced performance of their own technique on real ECG data.< >
A conference key distribution system (CKDS) can provide a common secret communication key to a set of M stations. A CKDS based on Lagrange interpolating polynomial is introduced. It is easy to see that breaking this s...
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A conference key distribution system (CKDS) can provide a common secret communication key to a set of M stations. A CKDS based on Lagrange interpolating polynomial is introduced. It is easy to see that breaking this system is equivalent to break the Diffie-Hellman public-key distribution system. This conference key is selected by the conference chairstation and hidden in the Lagrange interpolating polynomial. Recovering this key by each participating station only requires M-1 multiplications and M-2 additions over a finite field GF(P).< >
Q-uantitative dosimetry in clinical laser treatment requires information on propagation of light in tissue related to the optical properties of the tissue. This involves the solution of the integro-differential equati...
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