7,093 research outputs found
Digital Inequality
Unpicking and understanding if and how the web is linked to inequality means:
Recognising that the access divide is not over, Thinking beyond hardware, Thinking beyond demographic variables, Developing a conceptual and theoretical toolkit, Beyond technological determinism, Co-constitution, Intersectionality, Technical capita
Fatigue and fracture: Overview
A brief overview of the status of the fatigue and fracture programs is given. The programs involve the development of appropriate analytic material behavior models for cyclic stress-strain-temperature-time/cyclic crack initiation, and cyclic crack propagation. The underlying thrust of these programs is the development and verification of workable engineering methods for the calculation, in advance of service, of the local cyclic stress-strain response at the critical life governing location in hot section compounds, and the resultant crack initiation and crack growth lifetimes
Towards a Sociology of Organizational Space
This paper aims to contribute to, and extend, the emergent Sociology of organizational space. It engages critically with labour process approaches, which position space within a control-resistance paradigm, suggesting that the conceptualization of space embedded within these accounts is limited and limiting. Drawing on insights from cultural geography the paper uses a new empirical study to show the ways that spatial meanings and spatial practices in the micro-spaces of office life are constructed through diverse experiences, memories and identities operating at a range of spatial scales.Cultural Geography; Hot-desking; Labour Process; Organization; Space
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Evidence Cafes and Practitioner Cafes: Translating research into Police Practice
Current radical changes in the Police service internationally and in England and Wales are being driven by movements to adopt an Evidence-Based Practice (EBP) approach to policing. However this poses a challenge as early adopters have experienced resistance to EBP, a relatively unknown, and more importantly misunderstood approach for policing (Sherman, 2015). This resistance is not limited to police with international research highlighting implementation issues for evidence based medicine (Altman, 1996; Fairhurst & Dowrick, 1996; Murphy and Adams, 2005), evidence based management (Adams & Sasse, 1999; Rousseau, 2012), and evidence based teaching (Beista, 2007, Perry & Smart, 2007; Adams & Clough, 2015). One reason is the lack of training in EBP, which is coupled with recent concerns over the general quality of training and level of professionalism within UK police organisation (Davies et al, 1996). There have been international initiatives aimed at increasing learning around evidence based practice (Rousseau, 2012; Hall and Roussel, 2014). Some UK police forces have adopted approaches from other domains to counteract these problems (e.g. champions, enquiry visits). Mapping clear pathways that link training, experience and evidence-based practice is crucial to developing the capacity for an evidence-based workforce. This paper presents evidence from recent research that used evidence cafes and practitioner cafes connected to online resources as a route to increase understanding and awareness of evidence based practice amongst frontline police officers. Evidence cafes are coordinated by a knowledge exchange expert with an academic and a police practitioner who facilitate the translation of research into practice. This paper presents evidence of the benefit and limitations of these events. Analytics and learning analytics of events’ online resources also provide insights into these approaches and identify triggers for increased engagement across a wide geographical context
Life prediction modeling based on strainrange partitioning
Strainrange partitioning (SRP) is an integrated low-cycle-fatigue life predicting system. It was created specifically for calculating cyclic crack initiation life under severe high-temperature fatigue conditions. The key feature of the SRP system is its recognition of the interacting mechanisms of cyclic inelastic deformation that govern cyclic life at high temperatures. The SRP system bridges the gap between the mechanistic level of understanding that breeds new and better materials and the phenomenological level wherein workable engineering life prediction methods are in great demand. The system was recently expanded to address engineering fatigue problems in the low-strain, long-life, nominally elastic regime. This breakthrough, along with other advances in material behavior and testing technology, has permitted the system to also encompass low-strain thermomechanical loading conditions. Other important refinements of the originally proposed method include procedures for dealing with life-reducing effects of multiaxial loading, ratcheting, mean stresses, nonrepetitive (cumulative loading) loading, and environmental and long-time exposure. Procedure were also developed for partitioning creep and plastic strain and for estimating strainrange versus life relations from tensile and creep rupture properties. Each of the important engineering features of the SRP system are discussed and examples shown of how they help toward predicting high-temperature fatigue life under practical, although complex, loading conditions
Thermal fatigue durability for advanced propulsion materials
A review is presented of thermal and thermomechanical fatigue (TMF) crack initiation life prediction and cyclic constitutive modeling efforts sponsored recently by the NASA Lewis Research Center in support of advanced aeronautical propulsion research. A brief description is provided of the more significant material durability models that were created to describe TMF fatigue resistance of both isotropic and anisotropic superalloys, with and without oxidation resistant coatings. The two most significant crack initiation models are the cyclic damage accumulation model and the total strain version of strainrange partitioning. Unified viscoplastic cyclic constitutive models are also described. A troika of industry, university, and government research organizations contributed to the generation of these analytic models. Based upon current capabilities and established requirements, an attempt is made to project which TMF research activities most likely will impact future generation propulsion systems
Life prediction and constitutive behavior
One of the primary drivers that prompted the initiation of the hot section technology (HOST) program was the recognized need for improved cyclic durability of costly hot section components. All too frequently, fatigue in one form or another was directly responsible for the less than desired durability, and prospects for the future weren't going to improve unless a significant effort was mounted to increase our knowledge and understanding of the elements governing cyclic crack initiation and propagation lifetime. Certainly one of the important factors is the ability to perform accurate structural stress-strain analyses on a routine basis to determine the magnitudes of the localized stresses and strains since it is these localized conditions that govern the initiation and crack growth processes. Developing the ability to more accurately predict crack initiation lifetimes and cyclic crack growth rates for the complex loading conditions found in turbine engine hot sections is of course the ultimate goal of the life prediction research efforts. It has been found convenient to divide the research efforts into those dealing with nominally isotropic and anisotropic alloys; the latter for application to directionally solidified and single crystal turbine blades
Cyclic creep rupture behavior of three high temperature alloys
Tensile stress and tensile time-to-rupture relation determined from cyclic creep rupture tests on high temperature titanium alloy, cobalt alloy, and stainless stee
Coded Cooperative Data Exchange for a Secret Key
We consider a coded cooperative data exchange problem with the goal of
generating a secret key. Specifically, we investigate the number of public
transmissions required for a set of clients to agree on a secret key with
probability one, subject to the constraint that it remains private from an
eavesdropper.
Although the problems are closely related, we prove that secret key
generation with fewest number of linear transmissions is NP-hard, while it is
known that the analogous problem in traditional cooperative data exchange can
be solved in polynomial time. In doing this, we completely characterize the
best possible performance of linear coding schemes, and also prove that linear
codes can be strictly suboptimal. Finally, we extend the single-key results to
characterize the minimum number of public transmissions required to generate a
desired integer number of statistically independent secret keys.Comment: Full version of a paper that appeared at ISIT 2014. 19 pages, 2
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