9,729 research outputs found
Stability and Fourier-Mukai Transforms on Higher Dimensional Elliptic Fibrations
We consider elliptic fibrations with arbitrary base dimensions, and
generalise previous work by the second author. In particular, we check
universal closedness for the moduli of semistable objects with respect to a
polynomial stability that reduces to PT-stability on threefolds. We also show
openness of this polynomial stability. On the other hand, we write down
criteria under which certain 2-term polynomial semistable complexes are mapped
to torsion-free semistable sheaves under a Fourier-Mukai transform. As an
application, we construct an open immersion from a moduli of complexes to a
moduli of Gieseker stable sheaves on higher dimensional elliptic fibrations.Comment: 26 pages. Minor corrections. To appear in Comm. Anal. Geo
High Dynamic Range RF Front End with Noise Cancellation and Linearization for WiMAX Receivers
This research deals with verification of the high dynamic range for a heterodyne radio frequency (RF) front end. A 2.6 GHz RF front end is designed and implemented in a hybrid microwave integrated circuit (HMIC) for worldwide interoperability for microwave access (WiMAX) receivers. The heterodyne RF front end consists of a low-noise amplifier (LNA) with noise cancellation, an RF bandpass filter (BPF), a downconverter with linearization, and an intermediate frequency (IF) BPF. A noise canceling technique used in the low-noise amplifier eliminates a thermal noise and then reduces the noise figure (NF) of the RF front end by 0.9 dB. Use of a downconverter with diode linearizer also compensates for gain compression, which increases the input-referred third-order intercept point (IIP3) of the RF front end by 4.3 dB. The proposed method substantially increases the spurious-free dynamic range (DRf) of the RF front end by 3.5 dB
The higher rank local categorical DT/PT correspondence
In this paper we derive the higher rank local DT/PT models via the perverse
coherent systems on the resolved conifold and the extended ADHM quiver, as
critical loci. We generalize the categorical DT/PT correspondence by
P\u{a}durariu and Toda to higher ranks and obtain the categorical wallcrossing
formula as semiorthogonal decompositions.Comment: 15 pages. v2: presentation shortened. Comments are welcom
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