258,529 research outputs found
Design of Compact BPF and Planar Diplexer for UMTS using Embedded-scheme Resonator
A compact planar diplexer utilizing embedded-scheme resonator (ESR) is designed for universal mobile telecommunications system (UMTS). The ESR is formed by embedding interdigital resonators into an open loop resonator. Based on the proposed ESR, a narrowband bandpass filter suitable for diplexer design is proposed, fabricated and measured. The measured results demonstrate that the filter exhibits good transmission properties within band and high frequency selectivity. The rectangular area occupied by the filter has overall dimensions only 0.086λg by 0.105λg, promises good potential in wireless communication systems that require compact size and high encapsulation quality. Then, a compact planar diplexer operating at the TX-band of 1920-1980MHz and the RX-band of 2110-2170MHz, which is composed of a meander T-junction and two filters initially separately designed, is synthesized, simulated and measured. Both the simulated and measured results indicate that satisfied impedance matching and good isolation between two paths have been achieved
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Microstructural characterisation and thermal stability of an Mg-Al-Sr alloy prepared by rheo-diecasting
A commercial Mg-6Al-2Sr (AJ62) alloy has been prepared by a semisolid rheo-diecasting (RDC) process. The microstructure of the RDC alloy exhibits typical semisolid solidification features, i.e., 8.4 vol% primary α-Mg globules (23 μm in diameter), formed in the slurry maker at the primary solidification stage, uniformly distributed in the matrix of fine α-Mg grain size (8.2 μm) and intergranular eutectic Al4Sr lamellae, which resulted from secondary solidification inside the die. A ternary Mg-Al-Sr phase was also observed. Heat treatment revealed the extreme thermal stability of the RDC AJ62 alloy. The hardness showed little change up to 12 hours at 450°C, whilst the Al4Sr eutectic lamellae were broken up, spheroidised and coarsened during the annealing. The RDC alloy offers superior mechanical properties, especially ductility, over the same alloy produced by high pressure die-casting
Nearly Degenerate Gauginos and Dark Matter at the LHC
Motivated by dark-matter considerations in supersymmetric theories, we
investigate in a fairly model-independent way the detection at the LHC of
nearly degenerate gauginos with mass differences between a few GeV and about 30
GeV. Due to the degeneracy of gaugino states, the conventional leptonic signals
are likely lost. We first consider the leading signal from gluino production
and decay. We find that it is quite conceivable to reach a large statistical
significance for the multi-jet plus missing energy signal with an integrated
luminosity about 50 pb^-1 (50 fb^-1) for a gluino mass of 500 GeV (1 TeV). If
gluinos are not too heavy, less than about 1.5 TeV, this channel can typically
probe gaugino masses up to about 100 GeV below the gluino mass. We then study
the Drell-Yan type of gaugino pair production in association with a hard QCD
jet, for gaugino masses in the range of 100-150 GeV. The signal observation may
be statistically feasible with about 10 fb^-1, but systematically challenging
due to the lack of distinctive features for the signal distributions. By
exploiting gaugino pair production through weak boson fusion, signals of large
missing energy plus two forward-backward jets may be observable at a 4-6\sigma
level above the large SM backgrounds with an integrated luminosity of 100-300
fb^-1. Finally, we point out that searching for additional isolated soft muons
in the range p_T ~3-10 GeV in the data samples discussed above may help to
enrich the signal and to control the systematics. Significant efforts are made
to explore the connection between the signal kinematics and the relevant masses
for the gluino and gauginos, to probe the mass scales of the superpartners, in
particular the LSP dark matter.Comment: 35 pages, 32 figure
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