The authors present novel fault-tolerance schemes for 2-D systolic implementation of a recursive least squares minimization problem with applications to beamforming problems. They show that the errors can be detected ...
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The authors present novel fault-tolerance schemes for 2-D systolic implementation of a recursive least squares minimization problem with applications to beamforming problems. They show that the errors can be detected by examining only a few scalars. In the case of the transient errors the technique is self-correcting. The technique can be implemented with negligible algorithm modification and little additional hardware. The simplicity of the method invites its use in future systolic arrays.< >
The weighted checksum scheme has been proposed as a low-cost error detection procedure for parallel matrix computations. Error correction has proved to be a much more difficult problem to solve than detection when usi...
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Existing fault tolerance schemes have often been ignored by systolic array designers because they are too costly and unwieldy to implement. With this in mind, we have developed a new technique specially tailored for r...
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Analysis pervades all aspects of naval engineering. It is used to determine requirements for new or upgraded systems and to explore concepts for their employment. It is used to evaluate performance. It is used to esta...
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Analysis pervades all aspects of naval engineering. It is used to determine requirements for new or upgraded systems and to explore concepts for their employment. It is used to evaluate performance. It is used to establish design characteristics. And it comes in many varieties. This paper addresses use and misuse of analysis in naval engineering. The paper is oriented toward managers of analytic endeavors rather than the practitioners of analysis. It does not deal in depth with how to perform particular analytic techniques. Instead it discusses general principles that should guide both the selection and application of analytic techniques. The paper identifies problems which are frequently encountered in analyses related to naval engineering and suggests ways to ameliorate their deleterious effects. These problems are addressed from both the perspective of the manager of analysis and that of the user or consumer of results from the analysis. Some of the challenges that face naval engineering analyses as a consequence of hardware and software improvements and of more sophisticated systems are also discussed.
According to the definition of satisfaction of Boolean dependencies, Theorem 15 is not true for Boolean dependencies with negation. (A positive Boolean dependency is built using the Boolean connectives ⋏, ⋎, and ↛; a ...
According to the definition of satisfaction of Boolean dependencies, Theorem 15 is not true for Boolean dependencies with negation. (A positive Boolean dependency is built using the Boolean connectives ⋏, ⋎, and ↛; a general Boolean dependency (with negation) may use also the Boolean connective ¬.) Actually, the definition of satisfaction is not meaningful for Boolean dependencies with negation, since many are never satisfied. We show how the definition of satisfaction should be changed in order to make Boolean dependencies with negation meaningful and correct the *** associate with each relation r a set α(r) of truth assignments, as follows. For each pair of distinct tuples of r, the set α(r) contains the truth assignment that maps an attribute A to true if the two tuples are equal on A, and to false if the two tuples have different values for A. A Boolean dependency σ is satisfied by a relation r if σ (i.e., the corresponding Boolean formula) satisfies every truth assignment of α(r).The original definition given in the paper is equivalent to having α(r) also include the truth assignment that is generated by pairs in which both tuples are really the same tuple of r, that is, to having α(r) also always include the truth assignment τ mapping all attributes to true. Under that definition, however, many Boolean dependencies with negation are never satisfied and, hence, are meaningless. More precisely, according to the original definition, a Boolean dependency is satisfied by
The file allocation problem considers a file and a fully connected network having n nodes. The problem assumes that the overall file usage over a unit time period is known and it asks for the optimal set of network si...
The file allocation problem considers a file and a fully connected network having n nodes. The problem assumes that the overall file usage over a unit time period is known and it asks for the optimal set of network sites at which to locate copies of the file. This paper considers the same problem but it assumes that the behavior of the user access patterns changes over v planning periods in a manner, known in advance. A model is presented which shows that there are (2 n − 1) v possible file allocations. To assist the searching of this large solution space four theorems are presented which are subsequently utilized to analyze the problem and to solve an example case.
Severance and Lohman[1] proposed that all database amendments (i.e. additions, deletions and updates) are localized into a relatively small storage area, called a differential file. When the differential file grows su...
Severance and Lohman[1] proposed that all database amendments (i.e. additions, deletions and updates) are localized into a relatively small storage area, called a differential file. When the differential file grows sufficiently large, a reorganization incorporates all changes into a new generation of the database. This paper proposes a modification of the differential file approach in that the differential file only stores record additions. It is also concerned with the selection of the optimum reorganization points for both the original and the modified differential file approaches.
A crossassembler has been presented that provides the added features of control structures DO WHILE, DO UNTIL and IF-THEN-ELSE. The recent incorporation of these structures into many high-level languages via preproces...
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A crossassembler has been presented that provides the added features of control structures DO WHILE, DO UNTIL and IF-THEN-ELSE. The recent incorporation of these structures into many high-level languages via preprocessors or language extensions is one indication of the widely held belief that the exclusive use of these structures in algorithm development enhances the quality of the resulting software. With the current and expected growth of microsystem software, the early availability and use of programming tools such as the crossassembler will provide some hope that microsoftware will be of higher quality, and thus more reliabile than the previous generations of main-frame and minicomputer software.
A methodology for the study of deficiencies in large interconnected energy systems is presented. The solution to such problems involves the identification of strategies for the transfer of energy from available source...
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Following an introductory discussion on the implications of stochastic models of carcinogenesis on and of deterministic models for the growth kinetics of solid tumors, and a brief review of the experimental evidence, ...
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