27 research outputs found

    A View into the development of two comparable systems through the application of business re-engineering in an SME

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    Ideal Caravan Sales Ltd is a medium sized business with their headquarters in Durham, England. Their main business is the sale and transportation of static and touring caravans. Ideal Caravans (1С) have identified a process within their business which is not functioning adequately and does not allow the required control. As a result of this, they have decided to review that process and implement a computer system in order to rectify the problem. The company have also taken this opportunity to introduce a structured framework which they can apply to all future computer system developments. This thesis is an examination into the highlighted problem and discusses options available to the company. It considers off-the-shelf options as well as bespoke systems. The thesis also defines a structured approach for the company to use in the implementation of any future software systems. This will result in positioning the company so that it can clearly identify, design and implement new computer systems successfully whether internally or externally. The thesis also considers a comparison between two bespoke systems, identifying which is the most successful in solving the identified issue

    Powering the Academic Web

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    Context: Locating resources on the Web has become increasingly difficult for users and poses a number of issues. The sheer size of the Web means that despite what appears to be an increase in the amount of quality material available, the effort involved in locating that material is also increasing; in effect, the higher quality material is being diluted by the lesser quality. One such group affected by this problem is post-graduate students. Having only a finite amount of time to devote to research, this reduces their overall quality study time. Aim: This research investigates how post-graduate students use the Web as a learning resource and identifies a number of areas of concern with its use. It considers the potential for improvement in this matter by using a number of concepts such as: collaboration; peer reviewing and document classification and comparison techniques. This research also investigates whether by combining several of the identified technologies and concepts, student research on the Web can be improved. Method: Using some of the identified concepts as components, this research proposes a model to address the highlighted areas of concern. The proposed model, named the Durham Browsing Assistant (DurBA) is defined, and a number of key concepts which show potential within it are uncovered. One of the key concepts is chosen, that of document comparison. Given a source document, can a computer system reliably identify other documents which most closely match it from other on the Web? A software tool was created which allowed the testing of document comparison techniques, this was called the Durham Textual Comparison system (DurTeC) and it had two key concepts. The first was that it would allow various algorithms to be applied to the comparison process. The second concept was that it could simulate collaboration by allowing data to be altered, added and removed as if by multiple users. A set of experiments were created to test these algorithms and identify those which gave the best results. Results: The results from the experiments identified a number of the most promising relationships between comparison and collaboration processes. It also highlighted those which had a negative effect on the process, and those which produced variable results. Amongst the results, it was found that: 1. By providing DurTeC with additional source documents to the original, as if through a recommendation process, it was able to increase its accuracy substantially. 2. By allowing DurTeC to use synonym lists to expand its vocabulary, in many cases, it was found to have reduced its accuracy. 3. By restricting those words which DurTeC considered in its comparison process, based upon their value in the source document, accuracy could be increased. This could be considered as a form of collaborative keyword selection. Conclusion: This research shows that improvements can be made in the accuracy of identifying similar resources by using a combination of comparison and collaboration processes. The proposed model, DurBA would be an ideal host for such a system

    Studying Parton Energy Loss in Heavy-Ion Collisions via Direct-Photon and Charged-Particle Azimuthal Correlations

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    Charged-particle spectra associated with direct photon (γdir\gamma_{dir} ) and π0\pi^0 are measured in pp+pp and Au+Au collisions at center-of-mass energy sNN=200\sqrt{s_{_{NN}}}=200 GeV with the STAR detector at RHIC. A hower-shape analysis is used to partially discriminate between γdir\gamma_{dir} and π0\pi^0. Assuming no associated charged particles in the γdir\gamma_{dir} direction (near side) and small contribution from fragmentation photons (γfrag\gamma_{frag}), the associated charged-particle yields opposite to γdir\gamma_{dir} (away side) are extracted. At mid-rapidity (η<0.9|\eta|<0.9) in central Au+Au collisions, charged-particle yields associated with γdir\gamma_{dir} and π0\pi^0 at high transverse momentum (8<pTtrig<168< p_{T}^{trig}<16 GeV/cc) are suppressed by a factor of 3-5 compared with pp + pp collisions. The observed suppression of the associated charged particles, in the kinematic range η<1|\eta|<1 and 3<pTassoc<163< p_{T}^{assoc} < 16 GeV/cc, is similar for γdir\gamma_{dir} and π0\pi^0, and independent of the γdir\gamma_{dir} energy within uncertainties. These measurements indicate that the parton energy loss, in the covered kinematic range, is insensitive to the parton path length.Comment: submitted to Phys. Rev. Lett, 6 pages, 4 figure

    Observation of charge-dependent azimuthal correlations and possible local strong parity violation in heavy ion collisions

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    Parity-odd domains, corresponding to non-trivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge separation of quarks along the orbital momentum of the system created in non-central collisions. To study this effect, we investigate a three particle mixed harmonics azimuthal correlator which is a \P-even observable, but directly sensitive to the charge separation effect. We report measurements of this observable using the STAR detector in Au+Au and Cu+Cu collisions at sNN\sqrt{s_{NN}}=200 and 62~GeV. The results are presented as a function of collision centrality, particle separation in rapidity, and particle transverse momentum. A signal consistent with several of the theoretical expectations is detected in all four data sets. We compare our results to the predictions of existing event generators, and discuss in detail possible contributions from other effects that are not related to parity violation.Comment: 17 pages, 14 figures, as accepted for publication in Physical Review C

    Enhanced strange baryon production in Au+Au collisions compared to p+p at sqrts = 200 GeV

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    We report on the observed differences in production rates of strange and multi-strange baryons in Au+Au collisions at sqrts = 200 GeV compared to pp interactions at the same energy. The strange baryon yields in Au+Au collisions, then scaled down by the number of participating nucleons, are enhanced relative to those measured in pp reactions. The enhancement observed increases with the strangeness content of the baryon, and increases for all strange baryons with collision centrality. The enhancement is qualitatively similar to that observed at lower collision energy sqrts =17.3 GeV. The previous observations are for the bulk production, while at intermediate pT, 1 < pT< 4 GeV/c, the strange baryons even exceed binary scaling from pp yields.Comment: 7 pages, 4 figures. Printed in PR

    Charged and strange hadron elliptic flow in Cu+Cu collisions at sNN\sqrt{s_{NN}} = 62.4 and 200 GeV

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    We present the results of an elliptic flow analysis of Cu+Cu collisions recorded with the STAR detector at 62.4 and 200GeV. Elliptic flow as a function of transverse momentum is reported for different collision centralities for charged hadrons and strangeness containing hadrons KS0K_{S}^{0}, Λ\Lambda, Ξ\Xi, ϕ\phi in the midrapidity region eta<1.0|eta|<1.0. Significant reduction in systematic uncertainty of the measurement due to non-flow effects has been achieved by correlating particles at midrapidity, η<1.0|\eta|<1.0, with those at forward rapidity, 2.5<η<4.02.5<|\eta|<4.0. We also present azimuthal correlations in p+p collisions at 200 GeV to help estimating non-flow effects. To study the system-size dependence of elliptic flow, we present a detailed comparison with previously published results from Au+Au collisions at 200 GeV. We observe that v2v_{2}(pTp_{T}) of strange hadrons has similar scaling properties as were first observed in Au+Au collisions, i.e.: (i) at low transverse momenta, pT<2GeV/cp_T<2GeV/c, v2v_{2} scales with transverse kinetic energy, mTmm_{T}-m, and (ii) at intermediate pTp_T, 2<pT<4GeV/c2<p_T<4GeV/c, it scales with the number of constituent quarks, nqn_q. We have found that ideal hydrodynamic calculations fail to reproduce the centrality dependence of v2v_{2}(pTp_{T}) for KS0K_{S}^{0} and Λ\Lambda. Eccentricity scaled v2v_2 values, v2/ϵv_{2}/\epsilon, are larger in more central collisions, suggesting stronger collective flow develops in more central collisions. The comparison with Au+Au collisions which go further in density shows v2/ϵv_{2}/\epsilon depend on the system size, number of participants NpartN_{part}. This indicates that the ideal hydrodynamic limit is not reached in Cu+Cu collisions, presumably because the assumption of thermalization is not attained.Comment: 18 pages, 14 figure

    Measurements of ϕ\phi meson production in relativistic heavy-ion collisions at RHIC

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    We present results for the measurement of ϕ\phi meson production via its charged kaon decay channel ϕK+K\phi \to K^+K^- in Au+Au collisions at sNN=62.4\sqrt{s_{_{NN}}}=62.4, 130, and 200 GeV, and in p+pp+p and dd+Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV from the STAR experiment at the BNL Relativistic Heavy Ion Collider (RHIC). The midrapidity (y<0.5|y|<0.5) ϕ\phi meson transverse momentum (pTp_{T}) spectra in central Au+Au collisions are found to be well described by a single exponential distribution. On the other hand, the pTp_{T} spectra from p+pp+p, dd+Au and peripheral Au+Au collisions show power-law tails at intermediate and high pTp_{T} and are described better by Levy distributions. The constant ϕ/K\phi/K^- yield ratio vs beam species, collision centrality and colliding energy is in contradiction with expectations from models having kaon coalescence as the dominant mechanism for ϕ\phi production at RHIC. The Ω/ϕ\Omega/\phi yield ratio as a function of pTp_{T} is consistent with a model based on the recombination of thermal ss quarks up to pT4p_{T}\sim 4 GeV/cc, but disagrees at higher transverse momenta. The measured nuclear modification factor, RdAuR_{dAu}, for the ϕ\phi meson increases above unity at intermediate pTp_{T}, similar to that for pions and protons, while RAAR_{AA} is suppressed due to the energy loss effect in central Au+Au collisions. Number of constituent quark scaling of both RcpR_{cp} and v2v_{2} for the ϕ\phi meson with respect to other hadrons in Au+Au collisions at sNN\sqrt{s_{_{NN}}}=200 GeV at intermediate pTp_{T} is observed. These observations support quark coalescence as being the dominant mechanism of hadronization in the intermediate pTp_{T} region at RHIC.Comment: 22 pages, 21 figures, 4 table

    Identified high-pTp_{T} spectra in Cu+Cu collisions at sNN\sqrt{s_{NN}}=200 GeV

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    We report new results on identified (anti)proton and charged pion spectra at large transverse momenta (3<pTp_{T}<10 GeV/c) from Cu+Cu collisions at sNN\sqrt{s_{NN}}=200 GeV using the STAR detector at the Relativistic Heavy Ion Collider (RHIC). This study explores the system size dependence of two novel features observed at RHIC with heavy ions: the hadron suppression at high-pTp_{T} and the anomalous baryon to meson enhancement at intermediate transverse momenta. Both phenomena could be attributed to the creation of a new form of QCD matter. The results presented here bridge the system size gap between the available pp and Au+Au data, and allow the detailed exploration for the on-set of the novel features. Comparative analysis of all available 200 GeV data indicates that the system size is a major factor determining both the magnitude of the hadron spectra suppression at large transverse momenta and the relative baryon to meson enhancement.Comment: Submitted to Phys. Rev. C, 9 pages, 5 figure

    Hadronic resonance production in dd+Au collisions at sNN\sqrt{s_{_{NN}}} = 200 GeV at RHIC

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    We present the first measurements of the ρ(770)0\rho(770)^0, KK^*(892), Δ\Delta(1232)++^{++}, Σ\Sigma(1385), and Λ\Lambda(1520) resonances in dd+Au collisions at sNN\sqrt{s_{_{NN}}} = 200 GeV, reconstructed via their hadronic decay channels using the STAR detector at RHIC. The masses and widths of these resonances are studied as a function of transverse momentum (pTp_T). We observe that the resonance spectra follow a generalized scaling law with the transverse mass (mTm_T). The ofresonancesinminimumbiascollisionsiscomparedtothe of resonances in minimum bias collisions is compared to the of π\pi, KK, and pˉ\bar{p}. The ρ0/π\rho^0/\pi^-, K/KK^*/K^-, Δ++/p\Delta^{++}/p, Σ(1385)/Λ\Sigma(1385)/\Lambda, and Λ(1520)/Λ\Lambda(1520)/\Lambda ratios in dd+Au collisions are compared to the measurements in minimum bias p+pp+p interactions, where we observe that both measurements are comparable. The nuclear modification factors (RdAuR_{dAu}) of the ρ0\rho^0, KK^*, and Σ\Sigma^* scale with the number of binary collisions (NbinN_{bin}) for pT>p_T > 1.2 GeV/cc.Comment: STAR Collaboration. Submitted to PR

    Minijet deformation and charge-independent angular correlations on momentum subspace (η,ϕ)(\eta,\phi) in Au-Au collisions at sNN\sqrt{s_{NN}} = 130 GeV

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    First measurements of charge-independent correlations on angular difference variables η1η2\eta_1 - \eta_2 (pseudorapidity) and ϕ1ϕ2\phi_1 - \phi_2 (azimuth) are presented for primary charged hadrons with transverse momentum 0.15pt20.15 \leq p_t \leq 2 GeV/cc and η1.3|\eta| \leq 1.3 from Au-Au collisions at sNN=130\sqrt{s_{NN}} = 130 GeV. Strong charge-independent angular correlations are observed associated with jet-like structures and elliptic flow. The width of the jet-like peak on η1η2\eta_1 - \eta_2 increases by a factor 2.3 from peripheral to central collisions, suggesting strong coupling of semi-hard scattered partons to a longitudinally-expanding medium. New methods of jet analysis introduced here provide evidence for nonperturbative QCD medium effects in heavy ion collisions.Comment: 8 pages, 4 figure
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