As technology advances and our dependency on software increases, the requirement to develop the correct means to improve quality in both the deveiopment phase and the maintenance phase of software life cycle support b...
As technology advances and our dependency on software increases, the requirement to develop the correct means to improve quality in both the deveiopment phase and the maintenance phase of software life cycle support becomes increasingly significant. The focus of this paper is on the dilemma facing softwareengineering in maintaining quality within the constraints of the maintenance phase. The paper further proposes that the software maintenance process can also be analvzed and improved using statistical process control (SPC) techniques. The methods discussed in this paper have been proposed for use in the software Maintenance project at NUWC Detachment Norfolk. Upon successful testing at NUWC Detachment Norfolk, they will be forwarded to the AN/SQQ-89(V) (interagencv) software Quality Evaluation Committee for use by other agencies which are developing and maintaining AN/SQQ-89(V) software.
A tasking query language (TQL) for aiding very general analysis of Ada tasking in a Petri-net-based environment is discussed. An important principle of TQL's design is that of hiding the formalism upon which the a...
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Existence conditions are given for maximum likelihood parameter estimates for several commonly employed twoparameter software reliability models. For these models, the maximum likelihood equations can be expressed in ...
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The replication scheme of a distributed database determines how many replicas of each object are created, and to which processors these replicas are allocated. This scheme critically affects the performance of a distr...
Existence conditions are given for maximum likelihood parameter estimates for several commonly employed two-parameter software reliability models. For these models, the maximum likelihood equations can be expressed in...
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Existence conditions are given for maximum likelihood parameter estimates for several commonly employed two-parameter software reliability models. For these models, the maximum likelihood equations can be expressed in terms of a single equation in one unknown. Bounds are given on solutions to these single equations problems to serve as initial intervals for search algorithms like bisection. Uniqueness of the solutions is established in some cases. Results are given for the case of grouped failure data.< >
A tasking query language (TQL) for aiding very general analysis of Ada tasking in a Petri-net-based environment is discussed. An important principle of TQL's design is that of hiding the formalism upon which the a...
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A tasking query language (TQL) for aiding very general analysis of Ada tasking in a Petri-net-based environment is discussed. An important principle of TQL's design is that of hiding the formalism upon which the analysis framework is built. Instead, TQL defines a language by which queries of Ada interactions themselves can be expressed. Examples of TQL's capabilities are presented, and a sample analysis session using the gas station program is described.< >
A method for automating the search for codes that have particular structural features is described. A pattern language is used to specify the pattern of desired code. The benefits of using a pattern language include a...
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A method for automating the search for codes that have particular structural features is described. A pattern language is used to specify the pattern of desired code. The benefits of using a pattern language include a higher level of abstraction in specifying patterns and the power to specify complex patterns which are impossible to express in grep type languages. A system that accepts these patterns and locates code fragments in C source files is described.< >
The replication scheme of a distributed database determines how many replicas of each object are created, and to which processors these replicas are allocated. This scheme critically affects the performance of a distr...
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The replication scheme of a distributed database determines how many replicas of each object are created, and to which processors these replicas are allocated. This scheme critically affects the performance of a distributed system, since reading an object locally is less costly than reading it from a remote processor. Therefore in a read-intensive network a widely distributed replication is mandated. On the other hand, an update of an object is usually written to all, or a majority of the replicas, and therefore in a write-intensive network a narrowly distributed replication is mandated. In other words, the optimal replication scheme depends on the read-write pattern for each object. The authors propose a practical algorithm, called dynamic-data-allocation (DDA), that changes the replication scheme of an object (i.e. the processors which store a replica of the object) dynamically as the read-write pattern of the object changes in the network. They assume that the changes in the read-write pattern are not known a priori.< >
Poisson processes with failure intensity functions that are approximately constant are investigated. Maximum likelihood estimation procedures are used to estimate the failure intensity for a fixed level of approximati...
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Model selection based on a predictive performance measure is compared to model selection based on maximum likelihood. Both procedures exhibit unstable relative performance when predictive performance is measured over ...
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