9257101
More Powerful Z Data Refinement: Pushing the State of the Art in Industrial Refinement
We have recently completed the specification and full refinement proof of a large, industrial scale application. The application was security critical, and the modelling and proof was done to increase the client’s assurance that the implemented system had no design flaws with security implications. Here we describe the application, and then discuss an essential lesson to learn concerning large proof contracts: that one must forge a path between mathematical formality on the one hand and practical achievement of results on the other. We present a number of examples of such decision points, explaining the considerations that must be made in each case.
2090341
Z in practice
Using Z. Structure, Process, Fluency. The Established Strategy. Security Properties. Other Approaches to Z Specification. Validation. Putting Together Your Method. House Style. A Word Counting Utility. Roles in Space. Structuring a Video Shop. Promoting Snakes and Ladders. Refining the Tower of Hanoi. Be Abstract. Sets or Functions?. Sets, Quantifiers, or Toolkit?. Sequences are Functions are Relations are Sets. Error Handling Styles. Promotion. Using Free Types. Using Bags. A Function Calculator. Making Schemas Work for you. Exploiting the Power of the Language. A Real Number Toolkit. and Finally...
28202446
A demonstrably correct compiler
As critical applications grow in size and complexity, high level languages, rather than better-trusted assembly languages, will be used in their development. This adds potential for extra errors to creep in, especially in the now necessary compiler. To avoid these new errors, it is necessary to have a formal specification of the high level language, and a formal development of its compiler. We outline what we believe is a practical route for achieving a demonstrably correct compiler, and describe a prototype compiler we have built by this route for a small, but non-trivial, language.
60884961
The benefit of information technology in managing outcomes focused curriculum development across related degree programs
This paper describes an interactive, web-based tool that provides access to an Outcomes Database for managing an Outcomes Focused curriculum plan. The approach provides a rapid way to involve subject specialists, course controllers, curriculum designers and educational consultants in the curriculum design and review process. The Outcomes Database is used to capture the relationships between units (i.e. subjects), Unit Learning Outcomes, Course Learning Outcomes, Generic Graduate Attributes and assessments. This is undertaken across courses (i.e. undergraduate degree programs) sharing common units in Information Technology, Computer Science, and Software Engineering. Automatically generated database reports that show how units contribute to the development of the generic graduate attributes are compared to those derived manually on a unit-by-unit basis. Preliminary experience with this IT-based approach demonstrates that automatically generated database reports effectively highlight areas requiring further attention during subsequent curriculum development iterations. The tools and approach described here show how the Outcomes Database can assist in making the transition from an existing program to one using an Outcomes Focused approach.
35983610
Sorting of textual data bases: A variety generation approach to distribution sorting
Abstract A method of sorting large textual data-bases by computer using external storage is proposed. The range of sort-keys in a sample of data to be sorted is divided into a fixed set of partitions, which should also give an adequate representation of new data from a similar source. The partitions are composed of ordered key ranges. An incoming data stream is distributed into a series of bins according to the partition in which the key lies, and the bins are then seperately sorted, using an internal sort, to give an ordered file. It is shown how the number of disc accesses needed depends on the manner in which the bins become filled, and thus on statistics of the data. Experiments using an INSPEC data-base give information on which estimates of the efficiency of the method can be based.
6134873
Recognizing and Responding to Student Affect
This paper describes the use of wireless sensors to recognize student emotion and the use of pedagogical agents to respond to students with these emotions. Minimally invasive sensor technology has reached such a maturity level that students engaged in classroom work can us sensors while using a computer-based tutor. The sensors, located on each of 25 student's chair, mouse, monitor, and wrist, provide data about posture, movement, grip tension, facially expressed mental states and arousal. This data has demonstrated that intelligent tutoring systems can provide adaptive feedback based on an individual student's affective state. We also describe the evaluation of emotional embodied animated pedagogical agents and their impact on student motivation and achievement. Empirical studies show that students using the agents increased their math value, self-concept and mastery orientation.
24201818
Compression of Wiswesser Line Notations Using Variety Generation
36780179
President's information technology advisory committee (PITAC): subcommittee on transforming the government
A method for controlling a force-commutated inverter coupled between an electrochemical cell and a power grid for adjusting the magnitude and direction of the electrical energy flowing therebetween. Both the real power component and the reactive power component of AC electrical energy flow can be independently varied through the switching waveform presented to the intermediately coupled inverter. A var error signal is derived from a comparison of a var command signal with a signal proportional to the actual reactive power circulating between the inverter and the power grid. This signal is presented to a voltage controller which essentially varies only the effective magnitude of the fundamental voltage waveform out of the inverter, thereby leaving the real power component substantially unaffected. In a similar manner, a power error signal is derived by a comparison of a power command signal with a signal proportional to the actual real power flowing between the electrochemical cell and the power grid. This signal is presented to a phase controller which varies only the phase of the fundamental component of the voltage waveform out of the inverter relative to that of the power grid and changes only the real power in proportion thereto, thus leaving the reactive power component substantially unaffected.