5,584 research outputs found

    A structure marker study for Pd_2Si formation: Pd moves in epitaxial Pd_2Si

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    A sample with the configuration Si (111)/single crystalline Pd_2Si/polycrystalline Pd_2Si/Pd is used to study the dominant moving species during subsequent Pd_2Si formation by annealing at 275 °C. The interface between monocrystalline and polycrystalline Pd_2Si is used as a marker to monitor the dominant moving species. The result shows that Pd is the dominant moving species in the monocrystal

    Model for Anisotropic Directed Percolation

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    We propose a simulation model to study the properties of directed percolation in two-dimensional (2D) anisotropic random media. The degree of anisotropy in the model is given by the ratio μ\mu between the axes of a semi-ellipse enclosing the bonds that promote percolation in one direction. At percolation, this simple model shows that the average number of bonds per site in 2D is an invariant equal to 2.8 independently of μ\mu. This result suggests that Sinai's theorem proposed originally for isotropic percolation is also valid for anisotropic directed percolation problems. The new invariant also yields a constant fractal dimension Df1.71D_{f} \sim 1.71 for all μ\mu, which is the same value found in isotropic directed percolation (i.e., μ=1\mu = 1).Comment: RevTeX, 9 pages, 3 figures. To appear in Phys.Rev.

    Improvement of thermally formed nickel silicide by ion irradiation

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    A significant improvement of the lateral uniformity of thermally formed Ni_(2)Si layers has been observed after low‐dose (10^(13)~3 × 10^(14) ion/cm^2) Xe irradiation of an As‐deposited Ni film. Measurements have also been made on samples that contained a thin impurity layer formed intentionally between the silicon substrate and the evaporated nickel film. The impurity layer was thick enough to prevent thermal silicide formation in unirradiated samples, but in irradiated samples, the silicide formation was not prevented. Similar results were obtained for As implantations. We attribute this effect to ion mixing of the interfacial layer. These results demonstrate that a low‐dose irradiation can render the process of silicide formation by thermal annealing more tolerant to interfacial impurities. The concept is of potential significance to VLSI technology

    Assignment Model-based and Integrated Process Improvement (Mipi) to Integrate Waste Management System in Tpst Bantargebang-bekasi, West Java- Indonesia

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    . The waste management in Bantargebang has been planned for 15 yearsand should be improved in order to meet the needs of the stakeholders. The studyis done to find the right method to be used for integrating the waste managementin Bantargebang site. The method is a review of previous studies related toimprovement in waste management and business processes. The result suggeststhat the mapping of the process needs to be done on the waste managementsystem and using the Model-Based Integrated Process Improvement (MIPI) whichdeveloped by Adesola et al. (2006) to improve the process

    Synoptic Sky Surveys and the Diffuse Supernova Neutrino Background: Removing Astrophysical Uncertainties and Revealing Invisible Supernovae

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    The cumulative (anti)neutrino production from all core-collapse supernovae within our cosmic horizon gives rise to the diffuse supernova neutrino background (DSNB), which is on the verge of detectability. The observed flux depends on supernova physics, but also on the cosmic history of supernova explosions; currently, the cosmic supernova rate introduces a substantial (+/-40%) uncertainty, largely through its absolute normalization. However, a new class of wide-field, repeated-scan (synoptic) optical sky surveys is coming online, and will map the sky in the time domain with unprecedented depth, completeness, and dynamic range. We show that these surveys will obtain the cosmic supernova rate by direct counting, in an unbiased way and with high statistics, and thus will allow for precise predictions of the DSNB. Upcoming sky surveys will substantially reduce the uncertainties in the DSNB source history to an anticipated +/-5% that is dominated by systematics, so that the observed high-energy flux thus will test supernova neutrino physics. The portion of the universe (z < 1) accessible to upcoming sky surveys includes the progenitors of a large fraction (~ 87%) of the expected 10-26 MeV DSNB event rate. We show that precision determination of the (optically detected) cosmic supernova history will also make the DSNB into a strong probe of an extra flux of neutrinos from optically invisible supernovae, which may be unseen either due to unexpected large dust obscuration in host galaxies, or because some core-collapse events proceed directly to black hole formation and fail to give an optical outburst.Comment: 11 pages, 6 figure

    NUMERICAL AND EXPERIMENTAL MODELING OF INTERACTION BETWEEN A TURBULENT JET FLOW AND AN INLET

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    In ventilation devices to get rid of harmful substances out of workingplaces, we use sucking devices. The local sources of pollution are evacuated by them. Abasic element when creating the model of sucking device is: the source of harmful substancesis discussed as a rising convective flow, which is ejected out of sucking spectrum,created by a sucking apparatus. In the present work, the flow is a whole one with variablequantity of motion and kinetic energy along it's length. The change in those twoparameters is caused by and is in dependent function of the inlet spectrum. There hasbeen discussed a two-component flow of air and gas in ventilation devices. A two-velocityscheme of flow is used to realise the numerical method. An integral method of investigationis used, based on the conditions of conservation of mass contents, quantity of motion andkinetic energy. It's been accepted that quantity of motion and energy change in functionof inlet action. A comparison of numerical results and natural experiment are made fortwo conditions: full suck and not full suck. Conclusion is that the present model is preciseand can be unset for engineering calculations

    Computational Complexity of Atomic Chemical Reaction Networks

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    Informally, a chemical reaction network is "atomic" if each reaction may be interpreted as the rearrangement of indivisible units of matter. There are several reasonable definitions formalizing this idea. We investigate the computational complexity of deciding whether a given network is atomic according to each of these definitions. Our first definition, primitive atomic, which requires each reaction to preserve the total number of atoms, is to shown to be equivalent to mass conservation. Since it is known that it can be decided in polynomial time whether a given chemical reaction network is mass-conserving, the equivalence gives an efficient algorithm to decide primitive atomicity. Another definition, subset atomic, further requires that all atoms are species. We show that deciding whether a given network is subset atomic is in NP\textsf{NP}, and the problem "is a network subset atomic with respect to a given atom set" is strongly NP\textsf{NP}-Complete\textsf{Complete}. A third definition, reachably atomic, studied by Adleman, Gopalkrishnan et al., further requires that each species has a sequence of reactions splitting it into its constituent atoms. We show that there is a polynomial-time algorithm\textbf{polynomial-time algorithm} to decide whether a given network is reachably atomic, improving upon the result of Adleman et al. that the problem is decidable\textbf{decidable}. We show that the reachability problem for reachably atomic networks is Pspace\textsf{Pspace}-Complete\textsf{Complete}. Finally, we demonstrate equivalence relationships between our definitions and some special cases of another existing definition of atomicity due to Gnacadja

    Penetration of hot electrons through a cold disordered wire

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    We study a penetration of an electron with high energy E<<T through strongly disordered wire of length L<<a (a being the localization length). Such an electron can loose, but not gain the energy, when hopping from one localized state to another. We have found a distribution function for the transmission coefficient t. The typical t remains exponentially small in L/a, but with the decrement, reduced compared to the case of direct elastic tunnelling. The distribution function has a relatively strong tail in the domain of anomalously high t; the average ~(a/L)^2 is controlled by rare configurations of disorder, corresponding to this tail.Comment: 4 pages, 5 figure

    The potter wasp genus Allorhynchium from Vietnam, with descriptions of three new species and a new country record (Hymenoptera, Vespidae, Eumeninae)

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    Species of the potter wasp genus Allorhynchium van der Vecht (Eumeninae: Odynerini) occurring in Vietnam are presented. Seven species have been recorded from Vietnam. Of them, three species are described as new to science: Allorhynchium latum Nguyen, Tran & MT Nguyen, sp. nov., A. moerum Nguyen & AD Nguyen, sp. nov., and A. setosum Nguyen & Engel, sp. nov., and one species, A. argentatum (Fabricius, 1804), is recorded from Vietnam for the first time. An updated key to the Oriental species of the genus is presented
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