749 research outputs found

    Modeling of premixing-prevaporizing fuel-air mixing passages

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    The development of a computer program for the analytical prediction of the distribution of liquid and vapor fuel in the premixing-prevaporizing passage by the direct injection method is described. The technical approach adopted for this program is to separate the problem into three parts each with its own computer code. These three parts are: calculation of the two-dimensional or axisymmetric air flow; calculation of the three-dimensional fuel droplet evaporation; and calculation of the fuel vapor diffusion. This method of approach is justified because premixing passages operate at lean equivalence ratios. Hence, a weak interaction assumption can be made wherein the airflow can affect the fuel droplet behavior but the fuel droplet behavior does not affect the airflow

    Detecting time-fragmented cache attacks against AES using Performance Monitoring Counters

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    Cache timing attacks use shared caches in multi-core processors as side channels to extract information from victim processes. These attacks are particularly dangerous in cloud infrastructures, in which the deployed countermeasures cause collateral effects in terms of performance loss and increase in energy consumption. We propose to monitor the victim process using an independent monitoring (detector) process, that continuously measures selected Performance Monitoring Counters (PMC) to detect the presence of an attack. Ad-hoc countermeasures can be applied only when such a risky situation arises. In our case, the victim process is the AES encryption algorithm and the attack is performed by means of random encryption requests. We demonstrate that PMCs are a feasible tool to detect the attack and that sampling PMCs at high frequencies is worse than sampling at lower frequencies in terms of detection capabilities, particularly when the attack is fragmented in time to try to be hidden from detection

    Analytical modeling of operating characteristics of premixing-prevaporizing fuel-air mixing passages. Volume 2: User's manual

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    A user's manual describing the operation of three computer codes (ADD code, PTRAK code, and VAPDIF code) is presented. The general features of the computer codes, the input/output formats, run streams, and sample input cases are described

    Z' Physics

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    The limits on extra neutral gauge bosons, which could be reached at LEP2, are reviewed. Exclusion and discovery limits are discussed for f\bar f and WW production.Comment: 20 pages Latex, 7 figures included by epsfig, Contribution to the Proceedings the workshop "Physics at LEP2", Geneva, 199

    PerfWeb: How to Violate Web Privacy with Hardware Performance Events

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    The browser history reveals highly sensitive information about users, such as financial status, health conditions, or political views. Private browsing modes and anonymity networks are consequently important tools to preserve the privacy not only of regular users but in particular of whistleblowers and dissidents. Yet, in this work we show how a malicious application can infer opened websites from Google Chrome in Incognito mode and from Tor Browser by exploiting hardware performance events (HPEs). In particular, we analyze the browsers' microarchitectural footprint with the help of advanced Machine Learning techniques: k-th Nearest Neighbors, Decision Trees, Support Vector Machines, and in contrast to previous literature also Convolutional Neural Networks. We profile 40 different websites, 30 of the top Alexa sites and 10 whistleblowing portals, on two machines featuring an Intel and an ARM processor. By monitoring retired instructions, cache accesses, and bus cycles for at most 5 seconds, we manage to classify the selected websites with a success rate of up to 86.3%. The results show that hardware performance events can clearly undermine the privacy of web users. We therefore propose mitigation strategies that impede our attacks and still allow legitimate use of HPEs

    INCLUSIVE PARTICLE PRODUCTION IN \pbp COLLISIONS

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    We calculate the inclusive production of charged hadrons in \pbp collisions to next-to-leading order (NLO) in the QCD improved parton model using a new set of NLO fragmentation functions for charged pions and kaons. We predict transverse-momentum distributions and compare them with experimental data from the CERN S\pbpS Collider and the Fermilab Tevatron.Comment: the file containing the figures has been replaced: we correct a mistake in the uuencoding procedure and we give the real Fig 4 instead of the spurious one which was accidentally included in the previous file. the text is unchanged

    Pseudo Goldstones at Future Colliders from the Extended Bess Model

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    We consider the production of the lightest pseudo-Goldstone bosons at future colliders through the vector resonances predicted by the extended BESS model, which consists of an effective lagrangian parametrization with dynamical symmetry breaking, describing scalar, vector and axial-vector bound states in a rather general framework. We find that the detection of pseudo-Goldstone pairs at LHC requires a careful evaluation of backgrounds. For e+e- collisions in the TeV range the backgrounds can be easily reduced and the detection of pseudo-Goldstone pairs is generally easier.Comment: 17 pages and 12 figures (included as a uuencoded tar file), LaTeX (style article), UGVA-DPT 1994/03-84

    An Elusive Z' Coupled to Beauty

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    By extending the standard gauge group to SU(3)_c \times SU(2)_L \times U(1)_Y \times U(1)_X with X charges carried only by the third family we accommodate the LEP measurement of R_b and predict a potentially measurable discrepancy in A_{FB}^{b} in e^+e^- scattering and that D^0\bar{D}^0 mixing may be near its experimental limit. The Z', which explicitly violates the GIM mechanism, can nevertheless be naturally consistent with FCNC constraints. Direct detection of the Z' is possible but challenging.Comment: 12 pages, plus 1 Postscript figure, uses revtex, Discussion of FCNC extende
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