163,567 research outputs found

    Testing goodwill: Conflict and co-operation in new product development networks

    Get PDF
    Network forms are often seen as models of organisational flexibility, promoting the building of trust and exchange of information between different business functions while offering both cost savings and reductions in the uncertainties usually associated with innovation. Both internal and external networks have been identified as key elements in the collaborative development of new products. The actual process of network building and ongoing network management is not well researched, although the existing literature highlights difficulties for organisations attempting to maintain active product development networks. This article examines the development and management of such a network in the defence industry and focuses on network building processes in terms of the interactions between the individuals involved. This network has endured and evolved over many years despite a series of conflicts. One of the key findings is that the effective functioning of the overall network is closely allied to established processes within the two participating firms

    Impaired carotid viscoelastic properties in women with polycystic ovaries

    Get PDF
    Background-The purpose of this study was to assess the elastic properties of the carotid arteries in women with polycystic ovarian syndrome, asymptomatic women with polycystic ovaries. and healthy controls.Methods and Results-We recruited the following 60 subjects: 20 symptomatic women with polycystic ovaries attending the reproductive endocrinology clinics, 20 asymptomatic women with polycystic ovaries attending the family planning clinic, and 20 staff volunteers as healthy controls with normal ovaries on transvaginal scan. Compliance and stiffness index were assessed in the common and internal carotid arteries using duplex ultrasound equipped with an echo-locked arterial wall-tracking system. Compliance was significantly lower in the common carotid artery in symptomatic and asymptomatic women with polycystic ovaries than in the controls (10.7, 14.1, and 19.2%mm Hg-1 x 10(-2), respectively). The arterial stiffness index was correspondingly increased (12.3, 10.2, and 6.7, respectively). Similar results were obtained in the internal carotid artery for compliance (10.1. 11.0, and 16.9 %mm Hg-1 x 10(-2), respectively) and stiffness index (14.8, 16.2, and 8.7, respectively).Conclusions-The results of this study provide additional evidence of vascular dysfunction in women with polycystic ovaries and are compatible with the hypothesis that they are at increased risk from coronary artery disease and stroke

    Preliminary analysis of fuel tank impact

    Get PDF
    Following the accident involving the Air France Concorde in 2000 the effects of fluid structure interactions resulting from the impact of a fluid filled tank has become a cause for concern. The work reported here relates to the design of a series of experiments loosely based upon the Concorde incident which aimed to assess whether the probable failure mode in the Concorde accident could occur in land based vessels. Preliminary numerical analyses were undertaken for two of the nine cases that were investigated experimentally in which an empty tank was impacted by a projectile with a velocity of 14m/s and 21.9m/s Initial numerical results for the acceleration at two points on the tank surface and the deformation at the impact zone showed good agreement with test data. Future work is discussed including further numerical modelling incorporating fluid structure interactions for the analysis of the cases when the tank is partially full or completely full

    Colouration in crab spiders: substrate choice and prey attraction

    Get PDF
    Published version: http://jeb.biologists.org/content/208/10/1785/F3.expansio

    Probabilistic abductive logic programming using Dirichlet priors

    Get PDF
    Probabilistic programming is an area of research that aims to develop general inference algorithms for probabilistic models expressed as probabilistic programs whose execution corresponds to inferring the parameters of those models. In this paper, we introduce a probabilistic programming language (PPL) based on abductive logic programming for performing inference in probabilistic models involving categorical distributions with Dirichlet priors. We encode these models as abductive logic programs enriched with probabilistic definitions and queries, and show how to execute and compile them to boolean formulas. Using the latter, we perform generalized inference using one of two proposed Markov Chain Monte Carlo (MCMC) sampling algorithms: an adaptation of uncollapsed Gibbs sampling from related work and a novel collapsed Gibbs sampling (CGS). We show that CGS converges faster than the uncollapsed version on a latent Dirichlet allocation (LDA) task using synthetic data. On similar data, we compare our PPL with LDA-specific algorithms and other PPLs. We find that all methods, except one, perform similarly and that the more expressive the PPL, the slower it is. We illustrate applications of our PPL on real data in two variants of LDA models (Seed and Cluster LDA), and in the repeated insertion model (RIM). In the latter, our PPL yields similar conclusions to inference with EM for Mallows models

    High strength steel in fire

    Get PDF
    High-performance materials are necessary to meet the future demands of the construction industry, which is strongly influenced by a growing population and depletion of natural resources. Sustainable development is central to research and development into innovative structural materials, and requires solutions to be economically viable whilst equally providing a positive contribution towards environmental and social factors. High strength steels (HSS) have the potential to contribute towards such demands by reducing the weight of structures when employed in appropriate applications. Lighter structures require smaller foundations, shorter transportation and construction times and also lower CO2 emissions. A particular challenge related to the use of HSS in structures include increased likelihood of stability issues resulting from the reduction in section thickness, and limiting deflection and vibration criteria are also more likely to be critical. Nevertheless, when used appropriately, they can provide a sustainable solution. Their use in structural applications is further hindered by a lack of performance data and design guidance under fire conditions. This paper compares the mechanical properties, particularly strength and stiffness of HSS (yield strengths between 460-700 MPa) and mild steel (yields between 235-460 MPa) at elevated temperatures, through a critical review of published literature. Various alloying and processing routes used to achieve high yield strength are assessed. At the same time, the review considers available information on the strengthening mechanisms that can be utilised to retain the strength and/or stiffness of the material in the event of a fire. Using the information gathered, an extensive testing programme is developed which will enable design guidance for the fire design of HSS structures to be proposed.Engineering and Physical Sciences Research Council, TW

    On the mechanism of trailing vortex wandering

    Get PDF
    The mechanism of trailing vortex wandering has long been debated and is often attributed to either wind-tunnel effects or an instability. Using particle image velocimetry data obtained in the wake of a NACA0012 airfoil, we remove the effect of wandering from the measured velocity field and, through a triple decomposition, recover the coherent wandering motion. Based on this wandering motion, the most energetic structures are computed using the proper orthogonal decomposition (POD) and exhibit a helical mode with an azimuthal wavenumber of |m|=1 whose kinetic energy grows monotonically in the downstream direction. To investigate the nature of the vortex wandering, we perform a spatial stability analysis of a matched Batchelor vortex. The primary stability mode is found to be marginally stable and nearly identical in both size and structure to the leading POD mode. The strikingly similar structure, coupled with the measured energy growth, supports the proposition that the vortex wandering is the result of an instability. We conclude that the cause of the wandering is the non-zero radial velocity of the |m|=1 mode on the vortex centreline, which acts to transversely displace the trailing vortex, as observed in experiments. However, the marginal nature of the stability mode prevents a definitive conclusion regarding the specific type of instability

    Learning about sex: Results from Natsal 2000.

    Get PDF
    11-13 September 2002
    • ā€¦
    corecore