84,001 research outputs found
Iterative Detection of Diagonal Block Space Time Trellis Codes, TCM and Reversible Variable Length Codes for Transmission over Rayleigh Fading Channels
Iterative detection of Diagonal Block Space Time Trellis Codes (DBSTTCs), Trellis Coded Modulation (TCM) and Reversible Variable Length Codes (RVLCs) is proposed. With the aid of efficient iterative decoding, the proposed scheme is capable of providing full transmit diversity and a near channel capacity performance. The performance of the proposed scheme was evaluated when communicating over uncorrelated Rayleigh fading channels. Explicitly, significant iteration gains were achieved by the proposed scheme, which was capable of performing within 2~dB from the channel capacity
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Performance of bolted steel-beam to CFST-column joints using stiffened angles in column-removal scenario
This paper presents three experimental investigations on the performance of steel-beam to CFST-column joints using stiffened angle, long bolts and fin plate under a middle column removal scenario. Three specimens were designed and tested. The failure modes and catenary action are investigated in detail. The test results show that increasing the angle plate thickness at the joint could not only improve its performance significantly, but also trigger an early formation of catenary action. Increasing the length of short-limb had influence on the deformation ability of the proposed joint, rather than the load capacity. The buckling of stiffeners could prevent the brittle failure of the joints. With the contribution of catenary action, the joint shows much higher rotation capacities than that required in DoD design guidance. The initial stiffness of the joint was calculated using an analytical model with consideration of bolt pretension. Good agreement to the test results is achieved. A numerical analysis is also carried out, whose results show that adding additional row of bolts would improve the redundancy of the joint under column loss. An equivalent dynamic response evaluation of the joints was also performed. The results show that dynamic amplification coefficient should be worked out considering catenary action under large deformation
A Purely Symbol-Based Precoded and LDPC-Coded Iterative-Detection Assisted Sphere-Packing Modulated Space-Time Coding Scheme
In this contribution, we propose a purely symbol-based LDPC-coded scheme based on a Space-Time Block Coding (STBC) signal construction method that combines orthogonal design with sphere packing, referred to here as (STBCSP). We demonstrate that useful performance improvements may be attained when sphere packing aided modulation is concatenated with non-binary LDPC especially, when performing purely symbol-based turbo detection by exchanging extrinsic information between the non-binary LDPC decoder and a rate-1 non-binary inner precoder. We also investigate the convergence behaviour of this symbol-based concatenated scheme with the aid of novel non-binary Extrinsic Information Transfer (EXIT) Charts. The proposed symbol-based turbo-detected STBC-SP scheme exhibits a 'turbo-cliff' at Eb/N0 = 5.0 dB and achieves an Eb/N0 gain of 19.2dB at a BER of 10-5 over Alamouti’s scheme
Magnetically-induced reconstructions of the ground state in a few-electron Si quantum dot
We report unexpected fluctuations in the positions of Coulomb blockade peaks
at high magnetic fields in a small Si quantum dot. The fluctuations have a
distinctive saw-tooth pattern: as a function of magnetic field, linear shifts
of peak positions are compensated by abrupt jumps in the opposite direction.
The linear shifts have large slopes, suggesting formation of the ground state
with a non-zero angular momentum. The value of the momentum is found to be well
defined, despite the absence of the rotational symmetry in the dot.Comment: 5 pages, 4 figures, accepted to PR
Double-dot charge transport in Si single electron/hole transistors
We studied transport through ultra-small Si quantum dot transistors
fabricated from silicon-on-insulator wafers. At high temperatures, 4K<T<100K,
the devices show single-electron or single-hole transport through the
lithographically defined dot. At T<4K, current through the devices is
characterized by multidot transport. From the analysis of the transport in
samples with double-dot characteristics, we conclude that extra dots are formed
inside the thermally grown gate oxide which surrounds the lithographically
defined dot.Comment: 4 pages, 5 figures, to appear in Appl. Phys. Let
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