4,858 research outputs found

    Pultrusion process characterization

    Get PDF
    Pultrusion is a process through which high-modulus, lightweight composite structural members such as beams, truss components, stiffeners, etc., are manufactured. The pultrusion process, though a well-developed processing art, lacks a fundamental scientific understanding. The objective here was to determine, both experimentally and analytically, the process parameters most important in characterizing and optimizing the pultrusion of uniaxial fibers. The effects of process parameter interactions were experimentally examined as a function of the pultruded product properties. A numerical description based on these experimental results was developed. An analytical model of the pultrusion process was also developed. The objective of the modeling effort was the formulation of a two-dimensional heat transfer model and development of solutions for the governing differential equations using the finite element method

    Determination of wind tunnel constraint effects by a unified pressure signature method. Part 1: Applications to winged configurations

    Get PDF
    A new, fast, non-iterative version of the "Wall Pressure Signature Method" is described and used to determine blockage and angle-of-attack wind tunnel corrections for highly-powered jet-flap models. The correction method is complemented by the application of tangential blowing at the tunnel floor to suppress flow breakdown there, using feedback from measured floor pressures. This tangential blowing technique was substantiated by subsequent flow investigations using an LV. The basic tests on an unswept, knee-blown, jet flapped wing were supplemented to include the effects of slat-removal, sweep and the addition of unflapped tips. C sub mu values were varied from 0 to 10 free-air C sub l's in excess of 18 were measured in some cases. Application of the new methods yielded corrected data which agreed with corresponding large tunnel "free air" resuls to within the limits of experimental accuracy in almost all cases. A program listing is provided, with sample cases

    Determination of wind tunnel constraint effects by a unified pressure signature method. Part 2: Application to jet-in-crossflow

    Get PDF
    The development of an improved jet-in-crossflow model for estimating wind tunnel blockage and angle-of-attack interference is described. Experiments showed that the simpler existing models fall seriously short of representing far-field flows properly. A new, vortex-source-doublet (VSD) model was therefore developed which employs curved trajectories and experimentally-based singularity strengths. The new model is consistent with existing and new experimental data and it predicts tunnel wall (i.e. far-field) pressures properly. It is implemented as a preprocessor to the wall-pressure-signature-based tunnel interference predictor. The supporting experiments and theoretical studies revealed some new results. Comparative flow field measurements with 1-inch "free-air" and 3-inch impinging jets showed that vortex penetration into the flow, in diameters, was almost unaltered until 'hard' impingement occurred. In modeling impinging cases, a 'plume redirection' term was introduced which is apparently absent in previous models. The effects of this term were found to be very significant

    Predicting soil moisture conditions for arable free draining soils in Ireland under spring cereal crop production

    Get PDF
    peer-reviewedTemporal prediction of soil moisture and evapotranspiration has a crucial role in agricultural and environmental management. A lack of Irish models for predicting evapotranspiration and soil moisture conditions for arable soils still represents a knowledge gap in this particular area of Irish agro-climatic modelling. The soil moisture deficit (SMD) crop model presented in this paper is based on the SMD hybrid model for Irish grassland (Schulte et al., 2005). Crop and site specific components (free-draining soil) have been integrated in the new model, which was calibrated and tested using soil tension measurements from two experimental sites located on a well-drained soil under spring barley cultivation in south-eastern Ireland. Calibration of the model gave an R2 of 0.71 for the relationship between predicted SMD and measured soil tension, while model testing yielded R2 values of 0.67 and 0.65 (two sites). The crop model presented here is designed to predict soil moisture conditions and effective drainage (i.e., leaching events). The model provided reasonable predictions of soil moisture conditions and effective drainage within its boundaries, i.e., free-draining land used for spring cereal production under Irish conditions. In general, the model is simple and practical due to the small number of required input parameters, and due to model outputs that have good practical applicability, such as for computing the cumulative amount of watersoluble nutrients leached from arable land under spring cereals in free-draining soils

    Developing a service user informed intervention to improve participation and ability to perform daily activities in primary Sjögren’s syndrome: a mixed-methods study protocol

    Get PDF
    Introduction: A significant proportion of patients with primary Sjögren’s syndrome (PSS) is functionally impaired and experience difficulties participating in various aspects of everyday life. There is currently no evidence of efficacy for non-pharmacological interventions aimed specifically at supporting the patients with PSS to improve their participation and ability to perform daily activities. This paper describes a research protocol for a mixed-methods study to develop an intervention to improve these outcomes. The protocol follows the Medical Research Council framework for complex interventions. Methods and analysis: We will use group concept mapping with the patients, adults who live with them and healthcare professionals to identify factors which prevent people with PSS from participating in daily life and performing daily activities. The factors will be prioritised by participants for importance and feasibility and will inform an intervention to be delivered within a National Health Service (NHS) setting. Evidence-based intervention techniques will be identified for the prioritised factors and combined into a deliverable intervention package. Key stakeholders will comment on the intervention content and mode of delivery through focus groups, and the data will be used to refine the intervention. The acceptability and feasibility of the refined intervention will be evaluated in a future study. Ethics and dissemination: The study has been approved by an NHS Research Ethics Committee, REC Reference: 13/NI/0190. The findings of this study will be disseminated in peer-reviewed journals and through presentation at national and international conferences. Trial registration number: UKCRN Study ID: 15939

    Document Translation for Cross-Language Text Retrieval at the University of Maryland

    Get PDF
    The University of Maryland participated in three TREC-6 tasks: ad hoc retrieval, cross-language retrieval, and spoken document retrieval. The principal focus of the work was evaluation of a cross-language text retrieval technique based on fully automatic machine translation. The results show that approaches based on document translation can be approximately as effective as approaches based on query translation, but that additional work will be needed to develop a solid basis for choosing between the two in specific applications. Ad hoc and spoken document retrieval results are also presented
    • …
    corecore