449 research outputs found

    Tasking Event-B: An Extension to Event-B for Generating Concurrent Code

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    The Event-B method is a formal approach for modelling systems in safety-, and business-critical, domains. Initially, system specification takes place at a high level of abstraction; detail is added in refinement steps as the development proceeds toward implementation. Our aim has been to develop a novel approach for generating code, for concurrent programs, from Event-B. We formulated the approach so that it integrates well with the existing Event-B methodology and tools. In this paper we introduce a tasking extension for Event-B, with Tasking and Shared Machines. We make use of refinement, decomposition, and the extension, to structure projects for code generation for multitasking implementations. During the modelling phase decomposition is performed; decomposition reduces modelling complexity and makes proof more tractable. The decomposed models are then extended with sufficient information to enable generation of code. A task body describes a taskā€™s behaviour, mainly using imperative, programming-like constructs. Task priority and life-cycle (periodic, triggered, etc.) are also specified, but timing aspects are not modelled formally. We provide tool support in order to validate the practical aspects of the approach

    Building on the DEPLOY legacy: code generation and simulation

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    The RODIN, and DEPLOY projects have laid solid foundations for further theoretical, and practical (methodological and tooling) advances with Event-B; we investigated code generation for embedded, multi-tasking systems. This work describes activities from a follow-on project, ADVANCE; where our interest is co-simulation of cyber-physical systems. We are working to better understand the issues arising in a development when modelling with Event-B, and animating with ProB, in tandem with a multi-simulation strategy. With multi-simulation we aim to simulate various features of the environment separately, in order to exercise the deployable code. This paper has two contributions, the first is the extension of the code generation work of DEPLOY, where we add the ability to generate code from Event-B state-machine diagrams. The second describes how we may use code, generated from state-machines, to simulate the environment, and simulate concurrently executing state-machines, in a single task. We show how we can instrument the code to guide the simulation, by controlling the relative rate that non-deterministic transitions are traversed in the simulation

    Building on the DEPLOY Legacy: Code Generation and Simulation

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    The RODIN, and DEPLOY projects laid solid foundations for further theoretical, and practical (methodological and tooling) advances with Event-B. Our current interest is the co-simulation of cyber-physical systems using Event-B. Using this approach we aim to simulate various features of the environment separately, in order to exercise deployable code. This paper has two contributions, the first is the extension of the code generation work of DEPLOY, where we add the ability to generate code from Event-B state-machine diagrams. The second describes how we may use code, generated from state-machines, to simulate the environment, and simulate concurrently executing state-machines, in a single task. We show how we can instrument the code to guide the simulation, by controlling the relative rate that non-deterministic transitions are traversed in the simulation.Comment: In Proceedings of DS-Event-B 2012: Workshop on the experience of and advances in developing dependable systems in Event-B, in conjunction with ICFEM 2012 - Kyoto, Japan, November 13, 201

    Formal modelling for Ada implementations: tasking Event-B

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    This paper describes a formal modelling approach, where Ada code is automatically generated from the modelling artefacts. We introduce an implementation-level specification, Tasking Event-B, which is an extension to Event-B. Event-B is a formal method, that can be used to model safety-, and business-critical systems. The work may be of interest to a section of the Ada community who are interested in applying formal modelling techniques in their development process, and automatically generating Ada code from the model. We describe a streamlined process, where the abstract modelling artefacts map easily to Ada language constructs. Initial modelling takes place at a high level of abstraction. We then use refinement, decomposition, and finally implementation-level annotations, to generate Ada code. We provide a brief introduction to Event-B, before illustrating the new approach using small examples taken from a larger case study

    From Event-B models to code: sensing, actuating, and the environment

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    The Event-B method is a formal approach for modelling systems in safety-, and business-critical, domains. We focus, in this paper, on multi-tasking, embedded control systems. Initially, system specification takes place at a high level of abstraction; detail is added in refinement steps as the development proceeds toward implementation. In previous work, we presented an approach for generating code, for concurrent programs, from Event-B. Translators generate program code for tasks that access data in a safe way, using shared objects. We did not distinguish between tasks of the environment and those of the controller. The work described in this paper offers improved modelling and code generation support, where we separate the environment from the controller. The events in the system can participate in actuating or sensing roles. In the resulting code, sensing and actuation can be simulated using a form of subroutine call; or additional information can be provided to allow a task to read/write directly from/to a specfied memory location

    The Future of Higher Education for Land-Grant Institutions: Considerations Beyond Short-Term Strategic Planning

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    This research addresses future challenges for land-grant universities and calls on administrators to look beyond short-term strategic planning. Chapter One frames the research problem and presents a brief history of U.S. higher education defined by disruption and evolution. Statistical models provide a basis to identify future challenges for land-grant universities. I then propose to address those challenges by investigating University Industry Partnerships (UIP), increasing research productivity, and fostering sense of belonging for part-time graduate students. I use a systematic literature review of UIP structuring practices to reveal how UIPs are structured by time, personnel, and flexible horizontal organizational structures. I then use hermeneutical interpretative policy analysis to examine university research policies and research productivity. Findings from this policy analysis indicate institutional policies can positively influence research productivity when accompanied by investment in support and coordinated communication; consequences of institutional research policies are priorities are also addressed. Finally, I conducted a quantitative study to examine sense of belonging for part-time graduate students. Data analysis suggests existing measures of SB may need revision to accurately capture SB for part-time students. Findings indicate that positive academic outcomes are associated with higher levels of SB for part-time graduate students

    Avoiding programming for safety critical systems

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    The Discovery of Bicyclopyrone

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    Two short topics were presented in the lecture titled Some Highlights of an Agro Career presented at the Fall Meeting Swiss Chemical Society, September 10th, 2021. The first of these topics discussed the discovery of the selective corn herbicide Bicyclopyrone. The second topic presented was concerned with host marking pheromones (HMPs), and described the HMP of the Mexican fruit flyĀ anastrepha ludens, and its use in crop protection. The story concerning the host marking pheromones of the Mexican fruit fly has already been published in this journal[1] and thus this review will describe the discovery of Bicyclopyrone

    Stereochemical and trapping studies of biradicals

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    The work in this thesis can be divided into two parts. 1) Stereochemical studies Irradiation of cis-anti-5,6-[Ā²H]ā‚‚-2,3-diazablcyclo[2.2.2]oct-2-ene (dg-DBO) leads to bicyclo[2.2.0]hexane (BCH) in which the deuterium is predominantly exo, i.e. double inversion of configuration, and hexa-1,5-diene (HD) with equal amounts of cis and trans deuterium. In addition, direct photolysis affords small amounts of cyclohexene formed via a stereoselective 1,3-shift. The proportions of EE-, EZ-, and ZZ-dā‚‚-HDā€™s were not accessible by direct spectroscopic methods but could be obtained by a chemical method combined with mass spectrometry. Stereoselective substitution at the 1,6-positions, in which Z-deuterium was lost and E- deuterium retained, translated stereochemical information into deuterium content. The results of the analysis showed that the EZ-isotopomer was formed predominantly, but significant amounts of EE- and ZZ-isotopomers were also present. The results are compared to the pyrolysis stereochemistry of stereoselectively labelled dā‚‚-BCH and the known stereochemistry for the deazetation of DBO. A mechanism is proposed that accounts for all the observations. 2) Trapping studies While triplet biradicals have been intercepted by a wide range of biradical traps only one case of singlet biradicals, 2-alkylidenecyclopentane-l,3- diyls, are sufficiently long-lived to undergo intermolecular reactions. Related singlet biradicals have been proposed as intermediates in the photochemical rearrangement of a cyclic triene, 6-methylene-3,3- dimethylcyclohexa-1, 4-diene. When the triene was irradiated in the presence of olefins, 1:1 triene:olefin adducts could be isolated. Their structure was established by X-ray diffraction, spectroscopy, and independent synthesis. The mechanism of their formation is discussed
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