By classifying programs according to their relationship to the environment in which they are executed, the paper identifies the sources of evolutionary pressure on computer applications and programs and shows why this...
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By classifying programs according to their relationship to the environment in which they are executed, the paper identifies the sources of evolutionary pressure on computer applications and programs and shows why this results in a process of never ending maintenance activity. The resultant life cycle processes are then briefly discussed. The paper then introduces laws of Program Evolution that have been formulated following quantitative studies of the evolution of a number of different systems. Finally an example is provided of the application of Evolution Dynamics models to program release planning.
The Supervisory Control Theory was introduced in 1987 by Ramadge and Wonham (1987), and industrial applications are still scarce. This paper outlines an automatic code generation framework to construct the control log...
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This microcomputer controlled frequency synthesizer is a unique electronic television tuning system. It is a frequency synthesizer that always insures crystal stability by forcing the local oscillator in the tuner to ...
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This microcomputer controlled frequency synthesizer is a unique electronic television tuning system. It is a frequency synthesizer that always insures crystal stability by forcing the local oscillator in the tuner to assume the same stability as a fixed frequency crystal reference oscillator. Also, microcomputer controlled tuning provides many desireable features. The microcomputer controlled signal seek will only allow the system to stop on channels that are active. It can automatically adjust for MATV frequency offsets up to ±2MHz. There never is any programming either by the user or in the factory because the system automatically seeks to the channels that are active in its present location. There is a threshold control that allows the user to skip weak signals if he wishes. Manual fine tuning is available to increase the signal-to-noise ratio for fringe area reception or as a means of minimizing disturbing signals. Finally, the direct access channel entry is arranged to clear itself if the user is interrupted in the middle of a command.
Critical races in concurrent Ada programs are an insidious source of system errors. The Ada language does not have concurrency features to ease the development of critical race-free programs. We illustrate this using ...
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Critical races in concurrent Ada programs are an insidious source of system errors. The Ada language does not have concurrency features to ease the development of critical race-free programs. We illustrate this using the CRF language. CRF has extended the Ada language by the addition of a powerful caller selection mechanism. It is this facility that implements a discriminatory mutual exclusion (dimutex) construct, an important feature for building less critical race-prone programs. The MLog language supports the CRE caller selection mechanism, thus it is convenient as a rapid-prototyping platform. A design method for systematically converting CRF designs mb Ada designs is presented. The method uses a mixture of mechanical and creative transformations that are guaranteed not to introduce critical races. Helmbold and Luckham's gas-station example is used to illustrate the various approaches to applying the design method. [ABSTRACT FROM AUTHOR]
This paper discusses a model for finding an efficient implementation of a business application system whose logical specifications have been determined in advance. The model views file and program design as a problem ...
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This paper discusses a model for finding an efficient implementation of a business application system whose logical specifications have been determined in advance. The model views file and program design as a problem of systematically coordinating the configurations of datasets and computations. It uses a straightforward search technique to determine aggregations of computations, aggregations of datasets, device, organization, and key order for each dataset, key order for each computation, and access method for each dataset-computation pair. Although computational results are presented for a sample problem involving 54 computations and 49 datasets, the main point of the paper is that the underlying model works computationally and is simple enough to be adapted to many file design situations.
Moving horizon estimation (MHE) has proven to be an efficient optimization-based technique to address the problem of joint state and parameter estimation with nonlinearities in system dynamics and constraints. This wo...
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Although the problem of determining the minimum cost path through a graph arises naturally in a number of interesting applications, there has been no underlying theory to guide the development of efficient search proc...
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Although the problem of determining the minimum cost path through a graph arises naturally in a number of interesting applications, there has been no underlying theory to guide the development of efficient search procedures. Moreover, there is no adequate conceptual framework within which the various ad hoc search strategies proposed to date can be compared. This paper describes how heuristic information from the problem domain can be incorporated into a formal mathematical theory of graph searching and demonstrates an optimality property of a class of search strategies.
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