12,754 research outputs found

    Macroscopic Floquet topological crystalline steel pump

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    The transport of a steel sphere on top of two dimensional periodic magnetic patterns is studied experimentally. Transport of the sphere is achieved by moving an external permanent magnet on a closed loop around the two dimensional crystal. The transport is topological i.e. the steel sphere is transported by a primitive unit vector of the lattice when the external magnet loop winds around specific directions. We experimentally determine the set of directions the loops must enclose for nontrivial transport of the steel sphere into various directions

    Analysis of the protocol for the handover in a micro-cell packet switched mobile network

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    The overlay of microcells over macrocells offers new opportunities and is cost effective, which makes the handover in such a micro-cellular environment an important issue. The objective of this study is to analyze and prove the truthfulness of a new protocol proposed, which guarantees no packet loss during the handoff. The study here emphasizes on the data integrity issue, since it is the key factor affecting the throughput performance of the transport layer. It is shown that usage of the Internet Protocol leads to packet loss in the presence of handover. Simulation results reveal that the proposed new protocol preserves the data, even in the presence of handoff. A queuing model is built to illustrate the effect of data integrity on the gateway. Simulation results of this model exhibit the burden on the gateway. The three phases of the analysis mentioned above, are focused in displaying the data integrity issue

    Saturation Spectroscopy of Iodine in Hollow-core Optical Fibre

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    We present high-resolution spectroscopy of Iodine vapour that is loaded and trapped within the core of a hollow-core photonic crystal fibre (HC-PCF). We compare the observed spectroscopic features to those seen in a conventional iodine cell and show that the saturation characteristics differ significantly. Despite the confined geometry it was still possible to obtain sub-Doppler features with a spectral width of ~6 MHz with very high contrast. We provide a simple theory which closely reproduces all the key observations of the experiment.Comment: 12 pages, 7 figure

    School Site Visits: What can we learn from choice schools in Milwaukee?

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    The School Site Visits study is part of the fifth series of annual reports produced by the School Choice Demonstration Project (SCDP). It describes some of the major challenges experienced and common practices demonstrated by thirteen (13) K-12 schools participating in the Milwaukee Parental Choice Program (MPCP). During the 2010-11 school year, there were 107 religious and secular schools participating in the MPCP. This report is based on visits to six of the high schools and seven K-8 schools that collectively reflect the wide range of characteristics associated with participating schools. This includes whether schools scored above or below average on the 2010-11 Wisconsin Knowledge and Concepts Examinations in math and reading. Teams of researchers from the SCDP conducted one-day visits to each school during the spring and fall of 2011. Using a variety of interview, survey and observation instruments, the research teams gathered information about school practices in six general areas: (1) school culture, (2) student academic success, (3) effective leadership, (4) teacher quality, (5) religious integration and accommodation, and (6) school facilities. We use the data collected during the visits to describe the most common challenges the schools face and the common practices and strategies they use to overcome these challenges. Overall, a number of general lessons were learned

    Reconstructing and understanding the impacts of storms and surges, southern North Sea

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    Coastal barriers are ubiquitous globally and provide a vital protective role to valuable landforms, habitats and communities located to landward. They are, however, vulnerable to extreme water levels and storm wave impacts. A detailed record of sub-annual to annual; decadal; and centennial rates of shoreline retreat in frontages characterized by both high (> 3 m) and low (< 1 m) dunes is established for a barrier island on the UK east coast. For four storms (2006–2013) we match still water levels and peak significant wave heights against shoreline change at high levels of spatial densification. The results suggest that, at least in the short-term, shoreline retreat, of typically 5–8 m, is primarily driven by individual events, separated by varying periods of barrier stasis. Over decadal timescales, significant inter-decadal changes can be seen in both barrier onshore retreat rates and in barrier extension rates alongshore. Whilst the alongshore variability in barrier migration seen in the short-term remains at the decadal scale, shoreline change at the centennial stage shows little alongshore variability between a region of barrier retreat (at 1.15 m a1^{−1}) and one of barrier extension. A data-mining approach, synchronizing all the variables that drive shoreline change (still water level, timing of high spring tides and peak significant wave heights), is an essential requirement for validating models that predict future shoreline responses under changing sea level and storminess.This paper was completed while the first author (SB) was a recipient of a Leverhulme Research Fellowship (RF-2015-045) for a project entitled Development and Application of a shoreline response model. This paper is a contribution to NERC BESS Consortium grant A hierarchical approach to the examination of the relationship between biodiversity and ecosystem service flows across coastal margins (grant reference NE/J015423/1). Table 1 reports information gathered as part of an EU FP7 Collaborative Project (grant agreement no: 603458) Resilience-Increasing Strategies for Coasts – toolkit (http://www.risckit.eu).This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/esp.390
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