8,417 research outputs found

    Laser-welded corrugated core steel sandwich bridge decks

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    Steel bridge decks are often used for applications when a lightweight structure is sought for. Conventional orthotropic steel decks suffers from drawbacks in several aspects, including high production costs and durability problems. Corrugated Core Steel Sandwich Panels (CCSSPs) have shown a good potential to become the next generation lightweight bridge decks with enhanced structural properties compared to its predecessor. The work presented in this thesis aims at verifying CCSSPs for bridge applications and to gain an increased understanding of their structural behaviour. Even though considerable research effort related to all-steel sandwich panels has been made, focus in previous work has been on web-core sandwich panels. Very little work has been devoted to corrugated core panels, particularly with reference to bridge deck applications.\ua0\ua0\ua0\ua0\ua0\ua0 In this work, a production process is presented for the novel CCSSP. Four demonstrator panels, of C-Mn and Duplex stainless steel are produced. The production-dependent geometric properties of the panel are measured, and it is concluded that the production process give good quality of the panel. Within the measured variation of the geometric properties, the impact of this variation on the fatigue-relevant stresses is studied using numerical analyses. As an example, the results show strong impact of the weld-width and possible misalignment of the welds.\ua0\ua0\ua0\ua0\ua0\ua0 Fatigue is a highly important factor for steel bridge decks and it has a strong relation to durability and strength requirements that are put on the deck. Here, the fatigue-strength of laserwelds in CCSSPs is assessed using experiments and numerical analyses. The results show alignment to other previously performed fatigue tests, and that with respect to the effective notch stress approach, the current recommendations given in design codes can be used, with a presented restriction. In addition to the small-scale cell specimens, a panel-specimen is also tested under fatigue loading. The results from this test demonstrate high fatigue-performance of the CCSSP.\ua0\ua0\ua0\ua0\ua0 To ensure that structural requirements concerning stiffness and strength are satisfied, reliable analysis methods are needed. To find an optimal bridge deck topology, and to run many loadcases, these analyses also needs to be time-efficient. In this thesis, two approaches with these targets are evaluated using numerical analyses. The results show that it is possible to accurately predict stresses using a deformation driven sub-modelling approach. Incorporation of the deformability of the weld region is shown to have a high impact on the state of stress in the welds, and a modelling technique is presented in this aspect. In addition, equivalent stiffness properties of CCSSPs are investigated and derived herein. A general conclusion from this work is that the results validate the feasibility of using CCSSPs for bridge deck applications

    Computer-aided electronic circuit design, part I. Conduction processes in thin films, part II Status report, 1 Jun. - 30 Nov. 1965

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    Computer-aided electronic circuit design, and conduction processes in thin film

    Narrative Bytes : Data-Driven Content Production in Esports

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    Esports - video games played competitively that are broadcast to large audiences - are a rapidly growing new form of mainstream entertainment. Esports borrow from traditional TV, but are a qualitatively different genre, due to the high flexibility of content capture and availability of detailed gameplay data. Indeed, in esports, there is access to both real-time and historical data about any action taken in the virtual world. This aspect motivates the research presented here, the question asked being: can the information buried deep in such data, unavailable to the human eye, be unlocked and used to improve the live broadcast compilations of the events? In this paper, we present a large-scale case study of a production tool called Echo, which we developed in close collaboration with leading industry stakeholders. Echo uses live and historic match data to detect extraordinary player performances in the popular esport Dota 2, and dynamically translates interesting data points into audience-facing graphics. Echo was deployed at one of the largest yearly Dota 2 tournaments, which was watched by 25 million people. An analysis of 40 hours of video, over 46,000 live chat messages, and feedback of 98 audience members showed that Echo measurably affected the range and quality of storytelling, increased audience engagement, and invoked rich emotional response among viewers

    Linear and non-linear dynamic analyses of sandwich panels with face sheet-tocore debonding

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    А survey of recent developments in the dynamic analysis of sandwich panels with face sheet-to-core debonding is presented. The finite element method within the ABAQUSTM code is utilized. The emphasis is directed to the procedures used to elaborate linear and non-linear models and to predict dynamic response of the sandwich panels. Recently developed models are presented, which can be applied for structural health monitoring algorithms of real-scale sandwich panels. First, various popular theories of intact sandwich panels are briefly mentioned and a model is proposed to effectively analyse the modal dynamics of debonded and damaged (due to impact) sandwich panels. The influence of debonding size, form and location, and number of such damage on the modal characteristics of sandwich panels are shown. For nonlinear analysis, models based on implicit and explicit time integration schemes are presented and dynamic response gained with those models are discussed. Finally, questions related to debonding progression at the face sheet-core interface when dynamic loading continues with time are briefly highlighted

    Modeling and Design of Multi-Stable Composite Structures

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    L'abstract è presente nell'allegato / the abstract is in the attachmen

    Reuse Detector: Improving the management of STT-RAM SLLCs

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    Various constraints of Static Random Access Memory (SRAM) are leading to consider new memory technologies as candidates for building on-chip shared last-level caches (SLLCs). Spin-Transfer Torque RAM (STT-RAM) is currently postulated as the prime contender due to its better energy efficiency, smaller die footprint and higher scalability. However, STT-RAM also exhibits some drawbacks, like slow and energy-hungry write operations that need to be mitigated before it can be used in SLLCs for the next generation of computers. In this work, we address these shortcomings by leveraging a new management mechanism for STT-RAM SLLCs. This approach is based on the previous observation that although the stream of references arriving at the SLLC of a Chip MultiProcessor (CMP) exhibits limited temporal locality, it does exhibit reuse locality, i.e. those blocks referenced several times manifest high probability of forthcoming reuse. As such, conventional STT-RAM SLLC management mechanisms, mainly focused on exploiting temporal locality, result in low efficient behavior. In this paper, we employ a cache management mechanism that selects the contents of the SLLC aimed to exploit reuse locality instead of temporal locality. Specifically, our proposal consists in the inclusion of a Reuse Detector (RD) between private cache levels and the STT-RAM SLLC. Its mission is to detect blocks that do not exhibit reuse, in order to avoid their insertion in the SLLC, hence reducing the number of write operations and the energy consumption in the STT-RAM. Our evaluation, using multiprogrammed workloads in quad-core, eight-core and 16-core systems, reveals that our scheme reports on average, energy reductions in the SLLC in the range of 37–30%, additional energy savings in the main memory in the range of 6–8% and performance improvements of 3% (quad-core), 7% (eight-core) and 14% (16-core) compared with an STT-RAM SLLC baseline where no RD is employed. More importantly, our approach outperforms DASCA, the state-of-the-art STT-RAM SLLC management, reporting—depending on the specific scenario and the kind of applications used—SLLC energy savings in the range of 4–11% higher than those of DASCA, delivering higher performance in the range of 1.5–14% and additional improvements in DRAM energy consumption in the range of 2–9% higher than DASCA

    Trialing project-based learning in a new EAP ESP course: A collaborative reflective practice of three college English teachers

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    Currently in many Chinese universities, the traditional College English course is facing the risk of being ‘marginalized’, replaced or even removed, and many hours previously allocated to the course are now being taken by EAP or ESP. At X University in northern China, a curriculum reform as such is taking place, as a result of which a new course has been created called ‘xue ke’ English. Despite the fact that ‘xue ke’ means subject literally, the course designer has made it clear that subject content is not the target, nor is the course the same as EAP or ESP. This curriculum initiative, while possibly having been justified with a rationale of some kind (e.g. to meet with changing social and/or academic needs of students and/or institutions), this is posing a great challenge for, as well as considerable pressure on, a number of College English teachers who have taught this single course for almost their entire teaching career. In such a context, three teachers formed a peer support group in Semester One this year, to work collaboratively co-tackling the challenge, and they chose Project-Based Learning (PBL) for the new course. This presentation will report on the implementation of this project, including the overall designing, operational procedure, and the teachers’ reflections. Based on discussion, pre-agreement was reached on the purpose and manner of collaboration as offering peer support for more effective teaching and learning and fulfilling and pleasant professional development. A WeChat group was set up as the chief platform for messaging, idea-sharing, and resource-exchanging. Physical meetings were supplementary, with sound agenda but flexible time, and venues. Mosoteach cloud class (lan mo yun ban ke) was established as a tool for virtual learning, employed both in and after class. Discussions were held at the beginning of the semester which determined only brief outlines for PBL implementation and allowed space for everyone to autonomously explore in their own way. Constant further discussions followed, which generated a great deal of opportunities for peer learning and lesson plan modifications. A reflective journal, in a greater or lesser detailed manner, was also kept by each teacher to record the journey of the collaboration. At the end of the semester, it was commonly recognized that, although challenges existed, the collaboration was overall a success and they were all willing to continue with it and endeavor to refine it to be a more professional and productive approach
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