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11.
Efficient algorithms are derived for maximum likelihood (ML) soft-decision decoding of some binary self-dual codes. A family of easily decodable self-dual codes is derived by modifying a known F24, which has a weight distribution resembling that of the [24, 12, 8] Golay code G24. The ML decoding of F24 is accomplished by only 227 real additions, compared to 651 required for G24, yet the error rates of the two decoders are similar for moderate noise conditions 相似文献
12.
Enhancement of repair in experimental calvarial bone defects using calcium sulfate and dextran beads
Granular medical-grade calcium sulfate hemihydrate (MGCSH) and negatively charged dextran beads (DB) were evaluated both separately and in combination in cranial defects. Thirty-six rats received bilateral parietal inlay reconstructions using MGCSH, MGCSH plus DB, or DB alone or the defects were left unfilled. Postoperative evaluation at 45, 90, and 135 days was done by visual inspection, caliper measurements of defect thickness, and histologic examination. The best fibro-osseous repair of the defects occurred with the use of MGCSH in combination with DB. Repair tissue, which was confluent with the adjacent cranium, was noted to have good thickness, and a high bone content. By contrast, defects repaired with either DB or MGCSH alone had poorer quality repair tissue, with concavities, voids, bead migration, decreased thickness, and minimal bony replacement/ingrowth. Unfilled control defects showed only a thin, friable, translucent connective tissue layer of repair. No method produced complete bony closure. 相似文献
13.
Snyders J. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1991,37(4):1194-1200
A method whereby a substantially reduced family of error patterns, called survivors, may be created for maximum likelihood soft decoding is introduced. The family of survivor depends on the received word. A decoder based on this approach first forms the survivors, then scores them. Rather than obtaining the survivors by online elimination of error patterns, the use of predetermined lists that represent all families of survivors is proposed 相似文献
14.
Maximum likelihood soft decoding of binary block codes and decodersfor the Golay codes 总被引:1,自引:0,他引:1
Snyders J. Be'ery Y. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1989,35(5):963-975
Maximum-likelihood soft-decision decoding of linear block codes is addressed. A binary multiple-check generalization of the Wagner rule is presented, and two methods for its implementation, one of which resembles the suboptimal Forney-Chase algorithms, are described. Besides efficient soft decoding of small codes, the generalized rule enables utilization of subspaces of a wide variety, thereby yielding maximum-likelihood decoders with substantially reduced computational complexity for some larger binary codes. More sophisticated choice and exploitation of the structure of both a subspace and the coset representatives are demonstrated for the (24, 12) Golay code, yielding a computational gain factor of about 2 with respect to previous methods. A ternary single-check version of the Wagner rule is applied for efficient soft decoding of the (12, 6) ternary Golay code 相似文献
15.
Abdelhamid Boudiba Chao Zhang Polona Umek Carla Bittencourt Rony Snyders Marie-Georges Olivier Marc Debliquy 《International Journal of Hydrogen Energy》2013
WO3 loaded with noble metals is well-known to be sensitive to reducing gases and can be used as hydrogen sensor. This paper presents a simple and attractive method concerning the preparation of hydrogen sensors based on Pd-loaded WO3 nanocomposites with different morphologies. The influences of the morphology of WO3 and the palladium growth on its surface on the hydrogen sensing performances are studied. WO3 nanospheres, nanowires and nanolamellae were synthesized by different methods starting from the same precursor (H2WO4·nH2O) which has been obtained by acidification of sodium tungstate (Na2WO4). The prepared WO3 nanostructures were modified with the Pd by dispersing them in a PdCl2 containing solvent using sonication (giving Pd-WO3 inks). The sensors were prepared by screen-printing thick films (∼10 μm) of these inks on alumina substrates fitted with gold electrodes. The response of Pd-loaded WO3 sensors to hydrogen was checked for the different morphologies at working temperatures ranging from 180 to 240 °C. The sensors prepared from nanolamellae showed the highest response while the nanowires presented the shortest response time to hydrogen. 相似文献
16.
C. Nouvellon M. Michiels J.P. Dauchot C. Archambeau F. Laffineur E. Silberberg S. Delvaux R. Cloots S. Konstantinidis R. Snyders 《Surface & coatings technology》2012
In this study, reactive High Power Impulse Magnetron Sputtering (HiPIMS) experiments were carried out to synthesize titanium oxide films, using a 45 × 15 cm² titanium target in Ar/O2 gas mixtures. The deposition process was studied as a function of the peak current (ipeak) at constant voltage during the pulse (1 kV) and constant average power (Pav). As the oxygen flow was increased, ipeak was kept constant (160, 300 or 400A) by adjusting the pulse duration and the average power (2 or 4 kW) by adjusting the pulse repetition frequency. For all experimental conditions, an abrupt transition from metallic towards poisoned regimes was observed. The transition curves exhibit hysteresis. As ipeak is increased from 160 A to 450 A, for Pav = 4 kW, the oxygen content (Ω) in the Ar/O2 mixture needed to poison the target surface was reduced from Ω = 11.5% to Ω = 8.5%. These values are much smaller than those recorded for DC magnetron sputtering (DCMS) (Ω = 42%) and pulsed DCMS (Ω = 36%) experiments carried out at the same power. These results are explained by the enhancement of the ionization and dissociation rates of oxygen molecules with the increase of ipeak. 相似文献
17.
An error-trellis is a directed graph that represents all the sequences belonging to the coset which contains the symbol-by-symbol detected version of a given received sequence. A modular construction of error-trellises for an (n,k) convolutional code over GF(q) is presented. The trellis is designed on the basis of partitioning the scalar check matrix of the code into submatrices of l rows, accompanied with a corresponding segmentation of the syndrome. The value of the design parameter l is an essentially unconstrained multiple of n-k. For all the cosets of the code, the sections of the error-trellis are drawn from a collection of only ql modules; the module for each section is determined by the value of the associated syndrome segment. In case the construction is based on a basic polynomial check matrix, either canonical or noncanonical, then the error-trellis is minimal in the sense that σ⩽μ, where σ is the dimension of the state space of the trellis and μ is the constraint length of a canonical generator matrix for the code. For basic check matrices with delay-free columns, the inequality reduces to σ=μ 相似文献
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19.
Struzzi Claudia Scardamaglia Mattia Reckinger Nicolas Colomer Jean-François Sezen Hikmet Amati Matteo Gregoratti Luca Snyders Rony Bittencourt Carla 《Nano Research》2017,10(9):3151-3163
Nano Research - Suspended graphene is exposed to different fluorine-containing species produced by a plasma source fed with CF4 precursor gas. We investigate the fluorination process by selecting... 相似文献
20.
Satellite communications modeled by a feedforward random multiple-access system are considered. The transmission times of the users are governed by protocol signals. The authors consider the model of a slot-synchronized collision channel without feedback, proposed by J.L. Massey and P. Mathys (1985), augmented by interleavers that are essential for enabling the use of practical short codes. They assess the throughput of the channel on the basis of a short-coding error parameter. The set of parameters of all users characterizes the rate region achievable by employing short block codes with nonideal interleaving. The short-coding error parameter corresponds to a bound on the probability of error which is tighter than the bound expressed with the aid of the conventional cut-off rate. The analysis takes into account practical communication aspects, such as the effect of interleaving span and noise in noninterfered slots 相似文献