50,011 research outputs found

    Logical topology design for IP rerouting: ASONs versus static OTNs

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    IP-based backbone networks are gradually moving to a network model consisting of high-speed routers that are flexibly interconnected by a mesh of light paths set up by an optical transport network that consists of wavelength division multiplexing (WDM) links and optical cross-connects. In such a model, the generalized MPLS protocol suite could provide the IP centric control plane component that will be used to deliver rapid and dynamic circuit provisioning of end-to-end optical light paths between the routers. This is called an automatic switched optical (transport) network (ASON). An ASON enables reconfiguration of the logical IP topology by setting up and tearing down light paths. This allows to up- or downgrade link capacities during a router failure to the capacities needed by the new routing of the affected traffic. Such survivability against (single) IP router failures is cost-effective, as capacity to the IP layer can be provided flexibly when necessary. We present and investigate a logical topology optimization problem that minimizes the total amount or cost of the needed resources (interfaces, wavelengths, WDM line-systems, amplifiers, etc.) in both the IP and the optical layer. A novel optimization aspect in this problem is the possibility, as a result of the ASON, to reuse the physical resources (like interface cards and WDM line-systems) over the different network states (the failure-free and all the router failure scenarios). We devised a simple optimization strategy to investigate the cost of the ASON approach and compare it with other schemes that survive single router failures

    Economic changes and afforestation incentives in rural China

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    This paper uses provincial macro-data from the mid 1980s onwards to investigate the determinants of land-use choice in rural China, by paying particularattention to the decision to plant trees as competing with agriculture. The evidence supports the importance of economic motivations in the afforestation decision. A profitseeking behavior is found to be at stake in the decision to plant trees, which is made according to both the relative profitability of forestry against agriculture, and their relative risks. Afforestation is also found to strongly depend on the pressure upon land as well ason household wealth.afforestation incentives; rural China

    Silver nanoparticels obtained by sonochemical route

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    Poster presented at Adriatic School of Nanoscience – ASON-1, Dubrovnik, Croatia, September 19–23, 201

    Non-Abelian spin-orbit gauge: Persistent spin helix and quantum square ring

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    We re-express the Rashba and Dresselhaus interactions as non-Abelian spin-orbit gauges and provide a new perspective in understanding the persistent spin helix [Phys. Rev. Lett. 97, 236601 (2006)]. A spin-orbit interacting system can be transformed into a free electron gas in the equal-strength Rashba-Dresselhaus [001] linear model, the Dresselhaus [110] linear model, and a one-dimensional system. A general tight-binding Hamiltonian for non-uniform spin-orbit interactions and hoppings along arbitrary directions, within the framework of finite difference method, is obtained. As an application based on this Hamiltonian, a quantum square ring in contact with two ideal leads is found to exhibit four states, insulating, spin-filtering, spin-flipping, and spin-keeping states.Comment: 7 pages, 3 figure

    Changes in the chloride content of ground water in Pinellas County, Florida between 1947 and 1956

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    In December 1956 the U. S. Geological Survey, in cooperation with the Florida Geological Survey and the Board of County Commissioners of Pinellas County, collected waterlevel and chloride content of water in 94 wells in Pinellas County. First sampled in 1947, resampling and reanalyzing the water from these wells was used to determine the change in the chloride content of the ground water from 1947 to 1956. The chloride content of ground water is generally a reliable indication of the contamination of ground water by sea water, as 90 percent of the dissolved solids of sea water are chloride salts. (PDF contains 15 pages.

    Buyer Satisfaction with Residential Brokerage Services

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    This study employs ordered probit to estimate a model of buyer satisfaction with real estate brokerage services. The model provides evidence that: (1) satisfaction falls with length of search; (2) satisfaction is lower for married homebuyers; (3) satisfaction falls when the buyer experiences difficulty with housing finance; and (4) buyer satisfaction is increased when the broker fully discloses the requirements of the fair housing law.

    volume 2, no. 3 (Summer 1999)

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