57,300 research outputs found

    'It was absolute hell': inside the private prison

    Get PDF
    As part of a broader current of critique of the economic and political dynamics of prison privatisation - a critique that initially emanated from the USA - this paper focuses on Scotland and on research carried out at its then only private penal institution, HMP Kilmarnock. The authors dismantle the government's case for extending prison privatisation by drilling deep into the experience of Kilmarnock and demonstrating the deleterious effects of marketisation for prison officers and prisoners alike. Degraded pay and conditions and systemic understaffing corroded morale, exposed staff and inmates to risk, and contributed to massive officer turnover. Compelling evidence comes from sources ordinarily unavailable to critical researchers,such as internal company and government documentation

    Supercritical fuel injection system

    Get PDF
    a fuel injection system for gas turbines is described including a pair of high pressure pumps. The pumps provide fuel and a carrier fluid such as air at pressures above the critical pressure of the fuel. A supercritical mixing chamber mixes the fuel and carrier fluid and the mixture is sprayed into a combustion chamber. The use of fuel and a carrier fluid at supercritical pressures promotes rapid mixing of the fuel in the combustion chamber so as to reduce the formation of pollutants and promote cleaner burning

    Accounting for human rights : doxic health and safety practices - the accounting lessons from ICL

    Get PDF
    This paper is concerned with a specific human right - the right to work in a safe environment. It sets out a case for developing a new form of account of health and safety in any organisational setting. It draws upon the theoretical insights of Pierre Bourdieu taking inspiration from his assertion that in order to understand the 'logic' of the worlds we live in we need to immerse ourselves into the particularity of an empirical reality. In this case the paper, analyses a preventable industrial disaster which occurred in Glasgow, Scotland which killed nine people and injured 33 others. From this special case of what is possible, the paper unearths the underlying structures of symbolic violence of the UK State, the Health and Safety Executive and capital with respect to health and safety at work. While dealing with one specific country (Scotland), the analysis can be used to question health and safety regimes and other forms of symbolic violence across the globe

    Random walks which prefer unvisited edges : exploring high girth even degree expanders in linear time.

    Get PDF
    Let G = (V,E) be a connected graph with |V | = n vertices. A simple random walk on the vertex set of G is a process, which at each step moves from its current vertex position to a neighbouring vertex chosen uniformly at random. We consider a modified walk which, whenever possible, chooses an unvisited edge for the next transition; and makes a simple random walk otherwise. We call such a walk an edge-process (or E -process). The rule used to choose among unvisited edges at any step has no effect on our analysis. One possible method is to choose an unvisited edge uniformly at random, but we impose no such restriction. For the class of connected even degree graphs of constant maximum degree, we bound the vertex cover time of the E -process in terms of the edge expansion rate of the graph G, as measured by eigenvalue gap 1 -λmax of the transition matrix of a simple random walk on G. A vertex v is ℓ -good, if any even degree subgraph containing all edges incident with v contains at least ℓ vertices. A graph G is ℓ -good, if every vertex has the ℓ -good property. Let G be an even degree ℓ -good expander of bounded maximum degree. Any E -process on G has vertex cover time equation image This is to be compared with the Ω(nlog n) lower bound on the cover time of any connected graph by a weighted random walk. Our result is independent of the rule used to select the order of the unvisited edges, which could, for example, be chosen on-line by an adversary. © 2013 Wiley Periodicals, Inc. Random Struct. Alg., 00, 000–000, 2013 As no walk based process can cover an n vertex graph in less than n - 1 steps, the cover time of the E -process is of optimal order when ℓ =Θ (log n). With high probability random r -regular graphs, r ≄ 4 even, have ℓ =Ω (log n). Thus the vertex cover time of the E -process on such graphs is Θ(n)

    Buckling of conical shell with local imperfections

    Get PDF
    Small geometric imperfections in thin-walled shell structures can cause large reductions in buckling strength. Most imperfections found in structures are neither axisymmetric nor have the shape of buckling modes but rather occur locally. This report presents the results of a study of the effect of local imperfections on the critical buckling load of a specific axially compressed thin-walled conical shell. The buckling calculations were performed by using a two-dimensional shell analysis program referred to as the STAGS (Structural Analysis of General Shells) computer code, which has no axisymmetry restrictions. Results show that the buckling load found from a bifurcation buckling analysis is highly dependent on the circumferential arc length of the imperfection type studied. As the circumferential arc length of the imperfection is increased, a reduction of up to 50 percent of the critical load of the perfect shell can occur. The buckling load of the cone with an axisymmetric imperfections is nearly equal to the buckling load of imperfections which extended 60 deg or more around the circumference, but would give a highly conservative estimate of the buckling load of a shell with an imperfection of a more local nature

    The Power of Two Choices in Distributed Voting

    Full text link
    Distributed voting is a fundamental topic in distributed computing. In pull voting, in each step every vertex chooses a neighbour uniformly at random, and adopts its opinion. The voting is completed when all vertices hold the same opinion. On many graph classes including regular graphs, pull voting requires Θ(n)\Theta(n) expected steps to complete, even if initially there are only two distinct opinions. In this paper we consider a related process which we call two-sample voting: every vertex chooses two random neighbours in each step. If the opinions of these neighbours coincide, then the vertex revises its opinion according to the chosen sample. Otherwise, it keeps its own opinion. We consider the performance of this process in the case where two different opinions reside on vertices of some (arbitrary) sets AA and BB, respectively. Here, ∣A∣+∣B∣=n|A| + |B| = n is the number of vertices of the graph. We show that there is a constant KK such that if the initial imbalance between the two opinions is ?Îœ0=(∣A∣−∣B∣)/n≄K(1/d)+(d/n)\nu_0 = (|A| - |B|)/n \geq K \sqrt{(1/d) + (d/n)}, then with high probability two sample voting completes in a random dd regular graph in O(log⁥n)O(\log n) steps and the initial majority opinion wins. We also show the same performance for any regular graph, if Îœ0≄Kλ2\nu_0 \geq K \lambda_2 where λ2\lambda_2 is the second largest eigenvalue of the transition matrix. In the graphs we consider, standard pull voting requires Ω(n)\Omega(n) steps, and the minority can still win with probability ∣B∣/n|B|/n.Comment: 22 page

    Effect of organic, low-input and conventional production systems on yield and diseases in winter barley

    Get PDF
    The effect of organic, low-input and conventional management practices on barley yield and disease incidence was assessed in field trials over two years. Conventional fertility management (based on mineral fertiliser applications) and conventional crop protection (based on chemosynthetic pesticides) significantly increased the yield of winter barley as compared to organic fertility and crop protection regimes. Severity of leaf blotch (Rhynchosporium secalis) was highest under organic fertility and crop protection management and was correlated inversely with yield. For mildew (Erysiphe graminis), an interaction between fertility management and crop protection was detected. Conventional crop protection reduced severity of the disease, only under conventional fertility management. Under organic fertility management, incidence of mildew was low and application of synthetic pesticides in “low input” production systems had no significant effect on disease severity

    An experimental study of reactive turbulent mixing

    Get PDF
    An experimental study of two coaxial gas streams, which react very rapidly, was performed to investigate the mixing characteristics of turbulent flow fields. The center stream consisted of a CO-N2 mixture and the outer annular stream consisted of air vitiated by H2 combustion. The streams were at equal velocity (50 m/sec) and temperature (1280 K). Turbulence measurements were obtained using hot film anemometry. A sampling probe was used to obtain time averaged gas compositions. Six different turbulence generators were placed in the annular passage to alter the flow field mixing characteristics. The turbulence generators affected the bulk mixing of the streams and the extent of CO conversion to different degrees. The effects can be related to the average eddy size (integral scale) and the bulk mixing. Higher extents of conversion of CO to CO2 were found be increasing the bulk mixing and decreasing the average eddy size

    Elevated-temperature application of the IITRI compression test fixture for graphite/polyimide filamentary composites

    Get PDF
    Seventy-nine graphite/polyimide compression specimens were tested to investigate experimentally the IITRI test method for determining compressive properties of composite materials at room and elevated temperatures (589 K (600 F)). Minor modifications were made to the standard IITRI fixture and a high degree of precision was maintained in specimen fabrication and load alignment. Specimens included four symmetric laminate orientations. Various widths were tested to evaluate the effect of width on measured modulus and strength. In most cases three specimens of each width were tested at room and elevated temperature and a polynomial regression analysis was used to reduce the data. Scatter of replicate tests and back-to-back strain variations were low, and no specimens failed by instability. Variation of specimen width had a negligible effect on the measured ultimate strengths and initial moduli of the specimens. Measured compressive strength and stiffness values were sufficiently high for the material to be considered a usable structural material at temperatures as high as 589 K (600 F)
    • 

    corecore