125,065 research outputs found

    Migrant and non-migrant domestic workers in Hanoi: the segmentation of domestic service

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    Nguyen M. Migrants and Non-migrant Domestic Workers in Hanoi. The Segmentation of Domestic Service. DEV Working Paper Series. Vol 22. Norwich: School of International Development, UEA; 2010

    THE YIELD CURVE AS A LEADING INDICATOR ACROSS COUNTRIES AND TIME: THE EUROPEAN CASE

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    With the increasing demand for a better understanding about the relationship between yield curve and economic activities, this paper analyzes the data sets of seven countries in the European Union: Germany, France, Belgium, Spain, the United Kingdom, Sweden and Poland using quantitative analytical method. Based on previous literature, the expected hypothesis is: there is a strong relationship between the yield curve and the chance of an incoming economic contraction. The inverted yield curve, or the negative yield curve spread is considered as the tool to forecast the incoming contraction. Having been used as a rule of thumb for future reference of a contraction, whether yield curve and interest rates can be an accurate tool to predict the movement of business cycles should be studied more thoroughly, which will help not only the governments to reduce the loss from recession, but also equip financial sector valuable information to adjust itself before a contraction takes place. Further findings in this paper present a comparison between a group of Eurozone members and a group of non-Eurozone members. The similarities and differences give a broad idea of how the creation of the Eurozone has affected the area in the last decade

    Enhanced thermoelectric figure of merit in vertical graphene junctions

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    In this work, we investigate thermoelectric properties of junctions consisting of two partially overlapped graphene sheets coupled to each other in the cross-plane direction. It is shown that because of the weak van-der Waals interactions between graphene layers, the phonon conductance in these junctions is strongly reduced, compared to that of single graphene layer structures, while their electrical performance is weakly affected. By exploiting this effect, we demonstrate that the thermoelectric figure of merit can reach values higher than 1 at room temperature in junctions made of gapped graphene materials, for instance, graphene nanoribbons and graphene nanomeshes. The dependence of thermoelectric properties on the junction length is also discussed. This theoretical study hence suggests an efficient way to enhance thermoelectric efficiency of graphene devices.Comment: 6 pages, 4 figures, submitte

    The impact of NRZ data asymmetry on the performance of a space telemetry system

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    The telemetry data asymmetry due to rising and falling voltage transitions can cause undesired spectral components at the output of a spacecraft transmitter. The performance of a space telemetry system can potentially degrade because of these undesired components. Here, an expression is derived for the power spectral density of an asymmetric nonreturn-to-zero (NRZ) data stream. This formula is then used to investigate how the data bandwidth varies with data asymmetry. At the receiver end, the threshold levels of undesired spectral components that fall into the carrier-tracking-loop bandwidth are determined by examining the derived spectral density. Further, based on this formula, a simple technique is developed for the computation of bit signal-to-noise ratio (SNR) degradation due to data asymmetry. The telemetry bit SNR degradations derived using this technique are compared with results obtained previously and with measurements by the Electronic Systems Test Laboratory (ESTL) at the Lyndon B. Johnson Space Center

    Thermal conductivity of InAs/GaSb superlattice

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    The cross-plane thermal conductivity of a type II InAs/GaSb superlattice (T2SL) is measured from 13 K to 300 K using the 3{\omega} method. Thermal conductivity is reduced by up to 2 orders of magnitude relative to the GaSb bulk substrate. The low thermal conductivity of around 1-8 W/m\cdotK may serve as an advantage for thermoelectric applications at low temperatures, while presenting a challenge for T2SL quantum cascade lasers and high power light emitting diodes. We introduce a power-law approximation to model non-linearities in the thermal conductivity, resulting in increased or decreased peak temperature for negative or positive exponents, respectively.Comment: 4 pages, 3 figure

    Differential Amplify-and-Forward Relaying in Time-Varying Rayleigh Fading Channels

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    This paper considers the performance of differential amplify-and-forward (D-AF) relaying over time-varying Rayleigh fading channels. Using the auto-regressive time-series model to characterize the time-varying nature of the wireless channels, new weights for the maximum ratio combining (MRC) of the received signals at the destination are proposed. Expression for the pair-wise error probability (PEP) is provided and used to obtain an approximation of the total average bit error probability (BEP). The obtained BEP approximation clearly shows how the system performance depends on the auto-correlation of the direct and the cascaded channels and an irreducible error floor exists at high signal-to-noise ratio (SNR). Simulation results also demonstrate that, for fast-fading channels, the new MRC weights lead to a better performance when compared to the classical combining scheme. Our analysis is verified with simulation results in different fading scenarios
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