233,182 research outputs found

    A comparison of processing techniques for producing prototype injection moulding inserts.

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    This project involves the investigation of processing techniques for producing low-cost moulding inserts used in the particulate injection moulding (PIM) process. Prototype moulds were made from both additive and subtractive processes as well as a combination of the two. The general motivation for this was to reduce the entry cost of users when considering PIM. PIM cavity inserts were first made by conventional machining from a polymer block using the pocket NC desktop mill. PIM cavity inserts were also made by fused filament deposition modelling using the Tiertime UP plus 3D printer. The injection moulding trials manifested in surface finish and part removal defects. The feedstock was a titanium metal blend which is brittle in comparison to commodity polymers. That in combination with the mesoscale features, small cross-sections and complex geometries were considered the main problems. For both processing methods, fixes were identified and made to test the theory. These consisted of a blended approach that saw a combination of both the additive and subtractive processes being used. The parts produced from the three processing methods are investigated and their respective merits and issues are discussed

    Reducing risk in pre-production investigations through undergraduate engineering projects.

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    This poster is the culmination of final year Bachelor of Engineering Technology (B.Eng.Tech) student projects in 2017 and 2018. The B.Eng.Tech is a level seven qualification that aligns with the Sydney accord for a three-year engineering degree and hence is internationally benchmarked. The enabling mechanism of these projects is the industry connectivity that creates real-world projects and highlights the benefits of the investigation of process at the technologist level. The methodologies we use are basic and transparent, with enough depth of technical knowledge to ensure the industry partners gain from the collaboration process. The process we use minimizes the disconnect between the student and the industry supervisor while maintaining the academic freedom of the student and the commercial sensitivities of the supervisor. The general motivation for this approach is the reduction of the entry cost of the industry to enable consideration of new technologies and thereby reducing risk to core business and shareholder profits. The poster presents several images and interpretive dialogue to explain the positive and negative aspects of the student process

    Reinforcement Learning for Automatic Test Case Prioritization and Selection in Continuous Integration

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    Testing in Continuous Integration (CI) involves test case prioritization, selection, and execution at each cycle. Selecting the most promising test cases to detect bugs is hard if there are uncertainties on the impact of committed code changes or, if traceability links between code and tests are not available. This paper introduces Retecs, a new method for automatically learning test case selection and prioritization in CI with the goal to minimize the round-trip time between code commits and developer feedback on failed test cases. The Retecs method uses reinforcement learning to select and prioritize test cases according to their duration, previous last execution and failure history. In a constantly changing environment, where new test cases are created and obsolete test cases are deleted, the Retecs method learns to prioritize error-prone test cases higher under guidance of a reward function and by observing previous CI cycles. By applying Retecs on data extracted from three industrial case studies, we show for the first time that reinforcement learning enables fruitful automatic adaptive test case selection and prioritization in CI and regression testing.Comment: Spieker, H., Gotlieb, A., Marijan, D., & Mossige, M. (2017). Reinforcement Learning for Automatic Test Case Prioritization and Selection in Continuous Integration. In Proceedings of 26th International Symposium on Software Testing and Analysis (ISSTA'17) (pp. 12--22). AC

    Academic/industry innovations for sustainable building design and refurbishment

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    Development and efficient dissemination of innovations for sustainable building design and refurbishment are crucial for the competitiveness of companies operating in the construction sector which faces pressure to reduce levels of carbon emissions from existing and new buildings to zero. An overwhelming majority of companies operating in the construction sector in Scotland are small to medium size enterprises (SMEs) who do not have sufficient resources in the current economic downturn to undertake research in building design, products and processes that will make buildings more sustainable. A joint project of seven Scottish universities has been initiated to support collaboration with small to medium sized enterprises in developing and disseminating innovation for sustainable building design and refurbishment. The project concept and methods used for efficient dissemination of the project outputs to SMEs across Scotland are explained. An analysis of the outputs of completed feasibility studies and the provision of academic consultancy through the project indicates the range of problems tackled as well as trends in the development and use of innovations for a more sustainable built environment in Scotland

    Evolutionary improvement of programs

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    Most applications of genetic programming (GP) involve the creation of an entirely new function, program or expression to solve a specific problem. In this paper, we propose a new approach that applies GP to improve existing software by optimizing its non-functional properties such as execution time, memory usage, or power consumption. In general, satisfying non-functional requirements is a difficult task and often achieved in part by optimizing compilers. However, modern compilers are in general not always able to produce semantically equivalent alternatives that optimize non-functional properties, even if such alternatives are known to exist: this is usually due to the limited local nature of such optimizations. In this paper, we discuss how best to combine and extend the existing evolutionary methods of GP, multiobjective optimization, and coevolution in order to improve existing software. Given as input the implementation of a function, we attempt to evolve a semantically equivalent version, in this case optimized to reduce execution time subject to a given probability distribution of inputs. We demonstrate that our framework is able to produce non-obvious optimizations that compilers are not yet able to generate on eight example functions. We employ a coevolved population of test cases to encourage the preservation of the function's semantics. We exploit the original program both through seeding of the population in order to focus the search, and as an oracle for testing purposes. As well as discussing the issues that arise when attempting to improve software, we employ rigorous experimental method to provide interesting and practical insights to suggest how to address these issues

    Multi-objective improvement of software using co-evolution and smart seeding

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    Optimising non-functional properties of software is an important part of the implementation process. One such property is execution time, and compilers target a reduction in execution time using a variety of optimisation techniques. Compiler optimisation is not always able to produce semantically equivalent alternatives that improve execution times, even if such alternatives are known to exist. Often, this is due to the local nature of such optimisations. In this paper we present a novel framework for optimising existing software using a hybrid of evolutionary optimisation techniques. Given as input the implementation of a program or function, we use Genetic Programming to evolve a new semantically equivalent version, optimised to reduce execution time subject to a given probability distribution of inputs. We employ a co-evolved population of test cases to encourage the preservation of the program’s semantics, and exploit the original program through seeding of the population in order to focus the search. We carry out experiments to identify the important factors in maximising efficiency gains. Although in this work we have optimised execution time, other non-functional criteria could be optimised in a similar manner

    Impact of approaches in improving male partner involvement in the prevention of mother-to-child transmission (PMTCT) of HIV on the uptake of PMTCT services in sub-Saharan Africa: a protocol of a systematic review and meta-analysis

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    Introduction: Several studies have reported approaches used in improving the delivery of prevention of mother-to-child transmission (PMTCT) of HIV services through the involvement of male partners, but evidence from a systematic review is limited. We aim at determining the impact of male partner involvement on PMTCT in sub-Saharan Africa. Methods and analysis: This will be a systematic review of published literature. Interventional and observational studies on male involvement in PMTCT carried out in sub-Saharan Africa will be included irrespective of the year and language of publication. OVID Medline, Embase, PschINFO, and Cochrane database of controlled trials will be searched. After manual searching of articles, authors shall be contacted for further information. 2 authors (NFT and CJ) will independently screen potential articles for eligibility using defined inclusion and exclusion criteria. Critical Appraisal Skills Programme (CASP) tools, Jadad scale and the STROBE checklist will be used for critical appraisal, and the 2 authors will independently assess the quality of articles. Authors will independently extract data from studies using a pre-established data collection form, and any discrepancies will be sorted by a third author (TRK). Outcomes will be analysed using STATA V.12.0. The random effect model will be used to produce forest plots. The heterogeneity χ2 statistics and I2 will be used to assess for heterogeneity. Publication bias will be assessed using funnel plots. This protocol is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P) 2015 guidelines. Ethics and dissemination: No ethical approval since included studies will be published studies that had already obtained ethical approvals. The findings will guide HIV programmes on the best approaches towards involving male partners in PMTCT with a view to improving PMTCT services in sub-Saharan Africa
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