Noise filtering in binary pictures by combinatorial techniques

Filtering of noise in binary pictures includes both the filling of spurious gaps and the elimination of spurious connections. This paper describes a method which performs these operations by examining pairs of boundary points of the various objects in the picture. The current implementation uses only distance criteria, but it can be extended by taking into account local shape information.     

A comparison of time domains for software reliability models

A comparison of time domains (i.e., execution time vs. calendar time) is made for software reliability models, with the purpose of reaching some general conclusions about their relative desirability. The comparison is made by using a generic failure intensity function that represents a large majority of the principal models. The comparison is based on how well the function fits the estimated failure intensity, where the failure intensity is estimated with respect to both kinds of time. The failure intensity in each time domain is examined for trends. Failure intensity estimates are calculated from carefully collected data. The execution time domain is found to be highly superior to the calendar time domain.     

Morphismes et bimorphismes d'arbres

For every pair of positive integers n and p, there is a language accepted by a real-time deterministic pushdown automaton with n states and p stack symbols and size O(np), for which every context-free grammar needs at least n²p+1 nonterminals if n>1 (or p non-terminals if n = 1). It follows that there are context-free languages which can be recognized by pushdown automata of size O(np), but which cannot be generated by context-free grammars of size smaller than O(n²p); and that the standard construction for converting a pushdown automaton to a context-free grammar is optimal in the sense that it infinitely often produces grammars with the fewest number of nonterminals possible.     

Software project management audits

This paper shows how project audits can be used to uncover project strengths and weaknesses. Three audits are described and findings of the audit teams are summarized. Audits helped identify organizational problems, lacking management discipline, and software testing approaches useful to other projects. The issue of product sales versus disciplined project management was faced in all three audits. How this issue was handled is discussed and related to the success or lack of it for each project.     

An analysis of static metrics and faults in C software

In this empirical study, we evaluate the extent to which a set of software measures are correlated with the number of faults and the total estimated repair effort for a large software system. The measures we use are basic counts reflecting program size and structure and metrics proposed by McCabe and Halstead. The effect of program size has a major influence on these metrics, and we present a suitable method of adjusting the metrics for size. In modeling faults or repair effort as a function of one variable, a number of measures individually explain approximately one-quarter of the variation observed in the fault data. No one measure does significantly better than size in explaining the variation in faults found across software units, and thus multiple variable models are necessary to find metrics of importance in addition to program size. The “best” multivariate model explains approximately one-half the variation in the fault data. The metrics included in this model (in addition to size) are: the ratio of block comments to total lines of code, the number of decisions per function, and the relative vocabulary of program variables and operators. These metrics have potential for future use in the quality control of software.     

Modeling and analysis of data base organization: The doubly chained tree structure

The doubly-chained tree data base (file) organization is modeled and analyzed to obtain estimates of average access time (read-only) and total storage requirements. Macroscopic expressions are derived relating such performance measures to characteristic parameters of the specific data base, query or transaction traffic, storage devices and particular doubly-chained storage structure chosen. Important and generally applicable implementation-oriented aspects are considered. The model forms part of a prototype system for automatically analyzing and evaluating various data base organizations. The methodology and system are briefly outlined. Results for the doubly-chained structure using several real data bases are summarized, showing the rather large variability of performance as a function of both data base contents and complexity of queries.     

Parallels between software and VLSI engineering

The problems of VLSI design are discussed in the context of analogous software design issues. Current work in the areas of specification, methodology, support tools, and environments for both disciplines is detailed. The trends in VLSI design seem to be similar to earlier and current software design trends in these areas.     

Guest editor's introduction: Tool and methodology evaluation

The first ACM Sigsoft-sponsored Software Engineering Symposium focused on the issue of evaluating the effectiveness of software engineering tools, techniques, methods, and environments. In this paper we overview and summarize a collection of symposium papers that collectively indicate the state of development in the area of tool and methodology evaluation.     

Software complexity metric sensitivity to program structuring rules

Several studies have appeared in recent years examining the sensitivity of standard software complexity metrics to common rules of program structuring. In most cases, these studies found support for the use of certain metrics as indices of program quality as represented by program structure. In the research described in this paper, a broader analysis of metric sensitivity to the structuring rules was conducted. The conclusions reached differ greatly from those previously advocated in the literature; i.e., the metrics under consideration are shown to be relatively insensitive to program structure.     

Recent advances in the application of thermal infrared scanning to geological and hydrological studies

This paper describes recent advances in the development of thermal scanner technology, data processing techniques and theoretical simulation of field applications at the University of Newcastle. These developments have improved the potential of this method for practical field studies in geology and hydrology in the Australian environment. Improvements in technology have enabled the signal output of the scanner to be stabilized and calibrated by the use of internal, black-body temperature reference sources, prior to recording on magnetic tape. These improvements have opened a new dimension for the analysis and processing of thermal scanner data. Both analog and digital processing methods are used for analysis and presentation. Special presentation methods such as density slicing, contrast stretching, boundary enhancement and contouring are all used to enhance specific aspects of the data, which then assist the interpreter in gleaning additional information about his field problem. Advances have been made by the present group in theoretical studies of soil and rock temperature changes in an active thermal environment. Variations in the ground surface temperature during the diurnal cycle provide information relating to the ground thermal properties. Thus the thermal scanner can be used to study variations in the thermal properties of the ground surface over large areas. The application of thermal scanning to Australian Geological, Hydrogeological and Hydrological problems is discussed.     

Training learning strategies with computer-aided cooperative learning

This paper describes the combination of two potent training technologies (computer-based instruction and cooperative learning) into a system called computer-aided cooperative learning (CACL) and the use of CACL to train students in a general learning strategy. This six-steps strategy involves setting a task-appropriate mood, reading for general understanding, recall as much of the material as possible, detecting errors and omissions, elaborating upon the material to make it more memorable and reviewing. CACL capitalizes on the strengths and overcomes some of the weaknesses of each of the constituent technologies. The resulting program is described and some data demonstrating its effectiveness is presented. Students using CACL recalled more material from each of two passages studied individually than did students who did not use CACL. CACL appears to be a promising technology for the delivery of learning strategies. Future research and development efforts should examine CACL's usefulness to the training of more sophisticated learning strategies.     

System partitioning and its measure

Program modules and data structures are interconnected by calls and references in software systems. Partitioning these entities into clusters reduces complexity. For very large systems manual clustering is impractical. A method to perform automatic clustering is described and a metric to quantify the complexity of the resulting partition is developed.     

Embedded system design with ada as the system design language

Recent research in software engineering has produced a number of techniques for structuring an understanding of systems. Many of these techniques are applicable to the design of embedded computer systems and produce designs whose structures are easily expressible in the ada language. This language is itself structured so that the design of a system can be expressed independently of its implementation. Thus ada can be a useful system design language (SDL) with these techniques. This paper describes the software design problem in the development of embedded computer systems. It shows how ada can be used as an SDL, as well as a system implementation language. The essential point is that as an SDL ada encourages designers to use recent theory to develop better structures for their systems, and its subsequent use to implement the systems preserves those structures in the product.     

The elastic stability of square perforated plates

A direct matrix method of analysis for the buckling loads on structures, which had already been proven on various structural forms, is applied to the examination of the stability of flat square plates with central square perforations. The results for a variety of boundary conditions are presented for a range of hole to plate size from 0 to 0.8. The method generally shows trends which are different to those predicted by other numerical methods, particularly over the range of the larger hole sizes. Possible reasons for these differences are suggested, but further work to obtain definitive results is clearly needed by all investigators.     

The softest program test system

This paper reviews the current status of both research and commercial testing systems, and addresses the features necessary for a commercial test system. These include test case specification, test data generation, testbed generation, program instrumentation, automatic test execution and validation, as well as dynamic analysis of control and data flow. Of particular value is the linking of the details of the test to the program specification by means of an assertion language. These and other features are then described within the contest of , an integrated system for testing Assembler, , and / 1 programs in a simulated test environment. This system is now being used to validate programs in a test laboratory.     

Language extensions for specifying program access control policies in programming languages

The scope rules in programming languages control the sharing of data among program units, e.g., blocks and procedures. Typically, scope rules provide an all-or-nothing kind of access control. A wide range of programming problems exist which require finer access control as well as considerable sophistication for the implementation of access control policies on high-level data objects such as files. This paper presents a number of language extensions that permit the programmer to specify the degree of access control for each abstract object that a program can manipulate. The number of extensions has been kept as small as possible, while allowing the user to specify conveniently the access control policies that he desires. Some of the extensions permit access policies to be specified such that access correctness can be completely determined at compile time; other extensions permit policies to be specified that require some access checking to be done at run-time in order to ensure access correctness.     

The external structure: Experience with an automated module interconnection language

To study the problems of modifiable software, the Software Technology project has investigated approaches and methodologies that could improve modifiability. To test our approaches tools based on data abstraction—a design and programming language and a module interconnection language—were built and used. The incorporation of the module interconnection language into design altered the traditional model of system building. Introducing novices to our approach led to the formalization of new models of program design, development, and evaluation.     

Industrialization of weapon system software

A significant increase in weapon system software productivity is needed to reduce the current spiraling maintenance costs and to allow for the orderly introduction of new high technology computers during the 1980's. A low risk approach is proposed to solve this critical problem.     

A digital image system for atmospheric research

This paper describes the architecture of a medium scale digital image processing system developed as a research tool for analysis of meteorological data. The system is also being used for research on efficient image processing systems. Four qualitative performance measures for any image processor are introduced with specific application to the present machine. Preliminary results with noise reduction algorithms in satellite data are presented. Lastly, the versatility of the machine as a test bed for architectural studies of the computational structure of image processors with a microprogrammable control unit is discussed.