15,056 research outputs found
Broadside Dual-channel Orthogonal-Polarization Radiation using a Double-Asymmetric Periodic Leaky-Wave Antenna
The paper demonstrates that double unit-cell asymmetry in periodic leaky-wave
antennas (P-LWAs), i.e. asymmetry with respect to both the longitudinal and
transversal axes of the structure -- or longitudinal asymmetry (LA) and
transversal asymmetry (TA) -- allows for the simultaneous broadside radiation
of two orthogonal modes excited at the two ports of the antenna. This means
that the antenna may simultaneously support two orthogonal channels, which
represents an interesting polarization diversity characteristics for wireless
communications. The double asymmetric (DA) unit cell combines a circularly
polarized LA unit cell and a coupled mode TA unit cell, where the former
provides equal radiation in the series and shunt modes while the latter
separates these two modes in terms of their excitation ports. It is also shown
that the degree of TA in the DA unit cell controls the cross-polarization
discrimination level. The DA P-LWA concept is illustrated by two examples, a
series-fed line-connected patch (SF-LCP) P-LWA and a series-fed
capacitively-coupled patch (SF-CCP) P-LWA, via full-wave simulation and also
experiment for the SF-LCP P-LWA case
Modelling and Optimising of a Light-Weight Rockfall Catch Fence System
Rockfall catch fence is a mechanical barrier system that is used at the foot of cliffs to stop and retain falling rocks from reaching nearby infrastructures. A typical system comprises of a high tensile strength wire mesh that is anchored to the ground by rigid posts and strengthened to the lateral and upslope sides by anchoring tension cables. Additional components, such as shock absorbers, might be added to improve the system capacity to dissipate energy. This multi-component system characterises by geometrical complexity and high nonlinear response to impact loads.
A light-weight catch fence system is a simple system that can be easily installed in a time efficient manner using manpower rather than heavy machinery, which makes it ideal for railways located in mountainous and difficult terrain regions where there is difficulty in accessing sites with limited workspaces and restricted installation times. However, this should be combined with a proper design to ensure that the system provides the required protection to impede falling rocks from reaching the train lines. In this paper, a parametric study based on finite element analysis is developed to optimise the design of a light-weight catch fence system that has an energy absorption capacity of up to 100 kJ
Serialized Asynchronous Links for NoC
This paper proposes an asynchronous serialized link for NoC that can achieve the same levels of performance in terms of flits per second as a synchronous link but with a reduced number of wires in the point to point switch links and reduced power consumption. This is achieved by employing serialization in the asynchronous domain as opposed to synchronous to facilitate the removal of global clocking on the serial links. Based on transistor level simulations using 0.12 ?m foundry models it has been shown that it is possible to achieve the same level of performance as synchronous but with 75% reduction in wires and 65% reduction in power for a 300 MFlit/s link with 8 buffers with a switch clock speed of 300 MHz. Furthermore the paper presents the design requirements arising from interfacing switches of synchronous NoC and asynchronous serial links
Nonexistence of Entanglement Sudden Death in High NOON States
We study the dynamics of entanglement in continuous variable quantum systems
(CVQS). Specifically, we study the phenomena of Entanglement Sudden Death (ESD)
in general two-mode-N-photon states undergoing pure dephasing. We show that for
these states, ESD never occurs. These states are generalizations of the
so-called High NOON states, shown to decrease the Rayleigh limit of lambda to
lambda/N, which promises great improvement in resolution of interference
patterns if states with large N are physically realized. However, we show that
in dephasing NOON states, the time to reach V_crit, critical visibility, scales
inversely with N^2. On the practical level, this shows that as N increases, the
visibility degrades much faster, which is likely to be a considerable drawback
for any practical application of these states.Comment: 4 pages, 1 figur
REVIEW - A reference data set for retinal vessel profiles
This paper describes REVIEW, a new retinal vessel reference dataset. This dataset includes 16 images with 193 vessel segments, demonstrating a variety of pathologies and vessel types. The vessel edges are marked by three observers using a special drawing tool. The paper also describes the algorithm used to process these segments to produce vessel profiles, against which vessel width measurement algorithms can be assessed. Recommendations are given for use of the dataset in performance assessment. REVIEW can be downloaded from http://ReviewDB.lincoln.ac.uk
Memories of the future
The year is 2020. Sheffield University’s MSc in Electronic & Digital Library Management has been running for 10 years. What paths have its graduates’ careers taken
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