881 research outputs found

    Leveraging Lean in construction: A case study of a BIM-based HVAC manufacturing process

    Get PDF
    The impetus towards efficiency in the AECO (Architecture, Engineering, Construction & Operations) sector is driving the implementation of Lean practices. BIM technologies and BIM processes provide methods by which this can be achieved. Major clients of building services contractors have begun to mandate the use of BIM and some are using BIM preparedness/experience as pre-tender qualification criteria. In this case study, an initial review has been conducted of the achievements of a major Irish M&E contractor in implementing BIM. The firm purpose-built a facility for the off-site manufacture of building services components. The operations of the plant are efficient and qualityassured through the use of an appropriately skilled workforce at all stages of manufacture, and tracking software that has developed as the knowledge of the contractor grew. Standardised processes have been developed which have resulted in greater efficiencies and lower costs for the contractor as a result of fewer requirements for onsite modifications (such as those caused by clashes), less waste, and greater flexibility. Despite some initial objections, the employees of the company are now more satisfied with their working conditions and are, as a result, more productive. Through investment in BIM-based, Lean processes, the contractor can now better compete when tenerding for large-scale projects in Ireland and worldwide, including the rapidly-increasing number where BIM experience and preparedness is mandated

    Converting dark matter to dark radiation does not solve cosmological tensions

    Full text link
    Tensions between cosmological parameters (in particular the local expansion rate H0H_0 and the amplitude of matter clustering S8S_8) inferred from low-redshift data and data from the cosmic microwave background (CMB) and large-scale structure (LSS) experiments have inspired many extensions to the standard cosmological model, Λ\LambdaCDM. Models which simultaneously lessen both tensions are of particular interest. We consider one scenario with the potential for such a resolution, in which some fraction of the dark matter has converted into dark radiation since the release of the CMB. Such a scenario encompasses and generalizes the more standard "decaying dark matter" model, allowing additional flexibility in the rate and time at which the dark matter converts into dark radiation. In this paper, we constrain this scenario with a focus on exploring whether it can solve (or reduce) these tensions. We find that such a model is effectively ruled out by low-\ell CMB data, in particular by the reduced peak-smearing due to CMB lensing and the excess Integrated Sachs--Wolfe (ISW) signal caused by the additional dark energy density required to preserve flatness after dark matter conversion into dark radiation. Thus, such a model does not have the power to reduce these tensions without further modifications. This conclusion extends and generalizes related conclusions derived for the standard decaying dark matter model.Comment: 19 pages, 8 figures. Our modified Boltzmann code is available at https://github.com/fmccarthy/class_DMDR Re-uploaded with some more details on the failure of the DMDR model (v2); Reuploaded with the version published by PRD (v3

    Component-separated, CIB-cleaned thermal Sunyaev--Zel'dovich maps from Planck\textit{Planck} PR4 data with a flexible public needlet ILC pipeline

    Full text link
    We use the full-mission Planck\textit{Planck} PR4 data to construct maps of the thermal Sunyaev--Zel'dovich effect (Compton-yy parameter) in our Universe. To do so, we implement a custom needlet internal linear combination (NILC) pipeline in a Python package, pyilc\texttt{pyilc}, which we make publicly available. We publicly release our Compton-yy maps, which we construct using various constrained ILC ("deprojection") options in order to minimize contamination from the cosmic infrared background (CIB) in the reconstructed signal. In particular, we use a moment-based deprojection which minimizes sensitivity to the assumed frequency dependence of the CIB. Our code pyilc\texttt{pyilc} performs needlet or harmonic ILC on mm-wave sky maps in a flexible manner, with options to deproject various components on all or some scales. We validate our maps and compare them to the official Planck\textit{Planck} 2015 yy-map, finding that we obtain consistent results on large scales and 10-20%\% lower noise on small scales. We expect that these maps will be useful for many auto- and cross-correlation analyses; in a companion paper, we use them to measure the tSZ -- CMB lensing cross-correlation. We anticipate that pyilc\texttt{pyilc} will be useful both for data analysis and for pipeline validation on simulations to understand the propagation of foreground components through a full NILC pipeline.Comment: 28 pages, 15 figures. Public maps and other data products are available at https://users.flatironinstitute.org/~fmccarthy/ymaps_PR4_McCH23/ ; public code is available at https://github.com/jcolinhill/pyilc . V2: some additional notes about the effective CIB SED parameters and the halo model, also removed discussion about apodization of our maps and Planck map

    The Engineers' Bookshelf

    Get PDF
    Our perception of an object’s size arises from the integration of multiple sources of visual information including retinal size, perceived distance and its size relative to other objects in the visual field. This constructive process is revealed through a number of classic size illusions such as the Delboeuf Illusion, the Ebbinghaus Illusion and others illustrating size constancy. Here we present a novel variant of the Delbouef and Ebbinghaus size illusions that we have named the Binding Ring Illusion. The illusion is such that the perceived size of a circular array of elements is underestimated when superimposed by a circular contour – a binding ring – and overestimated when the binding ring slightly exceeds the overall size of the array. Here we characterize the stimulus conditions that lead to the illusion, and the perceptual principles that underlie it. Our findings indicate that the perceived size of an array is susceptible to the assimilation of an explicitly defined superimposed contour. Our results also indicate that the assimilation process takes place at a relatively high level in the visual processing stream, after different spatial frequencies have been integrated and global shape has been constructed. We hypothesize that the Binding Ring Illusion arises due to the fact that the size of an array of elements is not explicitly defined and therefore can be influenced (through a process of assimilation) by the presence of a superimposed object that does have an explicit size

    Third molar surgery: the patient's and the clinician's perspective

    Get PDF
    BACKGROUND: In this report, the problems of third molar surgery have been reviewed from the perspective of both patient and clinician; additionally an overall analysis of preoperative imaging investigations was carried out.Specifically, three main areas of interest were investigated: the prediction of surgical difficulty and potential complications; the assessment of stress and anxiety and finally the assessment of postoperative complications and the surgeon's experience. FINDINGS: In the first study, the prediction of surgical difficulty and potential injury to the inferior alveolar nerve was assessed. This was achieved by examining the patient's orthopantomograms and by using the Pederson Difficulty Index (PDI). Several radiological signs were identified and a classification tree was created to help predict the incidence of such event.In the second study, a prospective assessment addressing the patient's stress and anxiety pre-, intra- and postoperatively was employed. Midazolam was the active drug used against placebo. Objective and subjective parameters were assessed, including measuring the cortisol level in saliva. Midazolam was found to significantly reduce anxiety levels and salivary cortisol was identified as an accurate anxiety marker.In the third study, postoperative complications and the surgeon's experience were examined. Few patients in this study suffered permanent nerve dysfunction. Junior surgeons reported a higher complication rate particularly in trismus, alveolar osteitis, infection and paraesthesia over the distributions of the inferior alveolar and lingual nerves. In apparent contrast, senior surgeons reported higher incidence of postoperative bleeding. DISCUSSION: These studies if well employed can lead to favourable alteration in patient management and might have a positive impact on future healthcare service

    A novel powder-epoxy towpregging line for wind and tidal turbine blades

    Get PDF
    A novel material and process was developed using fibre-reinforced powder-epoxy to produce unidirectional towpreg with a pilot-scale towpregging line, for cost-effective production of large composite structures for the renewable energy market, specifically for wind and tidal turbine blades. Electrostatic attraction was used to coat fibre tows with powder epoxy and either joule or radiant heating employed to heat and melt the polymer, followed by consolidation between rollers. Unidirectional carbon-fibre and basalt-fibre reinforced polymer laminates (UD-CFRP and UD-BFRP, respectively) were manufactured from the towpreg. Tensile test results showed that the towpregging process could be employed to achieve high performance UD-CFRP with 0° tensile properties that are similar or better than commercially-available UD-CFRP systems. The competitive advantages of the powder-epoxy towpreg system include lower cost, better overall manufacturing control for vacuum-bag-only manufacturing and the ability to co-cure parts together at a later stage. Mechanical test results showed some variation between two types of UD-BFRP, but the results compared well with published data on UD-BFRP and equivalent glass-fibre reinforced polymer (GFRP) systems. Finally, the influence of hygrothermal ageing due to water immersion on the tensile properties of the materials was investigated, with tests revealing that the water ageing effect was more severe in the case of UD-BFRP than for UD-CFRP

    Systematic screening of 96 Schistosoma mansoni cell-surface and secreted antigens does not identify any strongly protective vaccine candidates in a mouse model of infection.

    Get PDF
    Background: Schistosomiasis is a major parasitic disease affecting people living in tropical and sup-tropical areas. Transmission of the parasite has been reported in 78 countries, causing significant morbidity and around 200,000 deaths per year in endemic regions. The disease is currently managed by the mass-administration of praziquantel to populations at risk of infection; however, the reliance on a single drug raises the prospect of parasite resistance to the only treatment widely available. The development of an effective vaccine would be a more powerful method of control, but none currently exists and the identification of new immunogens that can elicit protective immune responses therefore remains a priority. Because of the complex nature of the parasite life cycle, identification of new vaccine candidates has mostly relied on the use of animal models and on a limited set of recombinant proteins. Methods: In this study, we have established an infrastructure for testing a large number of vaccine candidates in mice and used it to screen 96 cell-surface and secreted recombinant proteins from Schistosoma mansoni. This approach, using standardised immunisation and percutaneous infection protocols, allowed us to compare an extensive set of antigens in a systematic manner. Results: Although some vaccine candidates were associated with a statistically significant reduction in the number of eggs in the initial screens, these observations could not be repeated in subsequent challenges and none of the proteins studied were associated with a strongly protective effect against infection. Conclusions: Although no antigens individually induced reproducible and strongly protective effects using our vaccination regime, we have established the experimental infrastructures to facilitate large-scale systematic subunit vaccine testing for schistosomiasis in a murine infection model. Copyright: © 2019 Crosnier C et al
    corecore