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1.
Capacity-achieving sequences for the erasure channel 总被引:6,自引:0,他引:6
Oswald P. Shokrollahi A. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2002,48(12):3017-3028
This paper starts a systematic study of capacity-achieving (c.a.) sequences of low-density parity-check codes for the erasure channel. We introduce a class A of analytic functions and develop a procedure to obtain degree distributions for the codes. We show various properties of this class which help us to construct new distributions from old ones. We then study certain types of capacity-achieving sequences and introduce new measures for their optimality. For instance, it turns out that the right-regular sequence is c.a. in a much stronger sense than, e.g., the Tornado sequence. This also explains why numerical optimization techniques tend to favor graphs with only one degree of check nodes. 相似文献
2.
Eslami Vahideh Ashofteh Parisa-Sadat Golfam Parvin Loáiciga Hugo A. 《Water Resources Management》2021,35(12):4085-4110
Water Resources Management - Environmental Impact Assessments (EIAs) of development projects are necessary to minimize negative impacts and maximize benefits. The objective of this paper is to... 相似文献
3.
Magnetic susceptibility measurements of high purity MgO single crystals (<50-wt. ppm transition metals) by means of a vibrating-sample magnetometer shows an anomaly at 800 K. At the same temperature the electric conductivity increases anomalously, the static dielectric constant epsilon increases from 9 to approximately 150, a pronounced positive surface charge appears, and Fe2+ in the MgO matrix oxidizes to Fe3+. The data are consistent with O2(2-) (peroxy) defects, representing self-trapped, spin-paired positive holes at Mg2+ vacancy sites. Diamagnetic at low temperatures, the holes start to decouple their spins > 600 K, probably forming at first V0 centers (two O- at an Mg2+ vacancy), then V- centers (single O- at an Mg2+ vacancy), and releasing mobile O- states. These O- represent itinerant charge carriers on acceptor levels near the O 2p-dominated valence band and conduct by O- /O2- valency fluctuations. The O- concentration is of the order of 8 X 10(19) cm-3. 相似文献
4.
Rastegari Parvin Susilo Willy Dakhilalian Mohammad 《International Journal of Information Security》2019,18(5):619-635
International Journal of Information Security - In a designated verifier signature (DVS) scheme, the signer (Alice) creates a signature which is only verifiable by a designated verifier (Bob).... 相似文献
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Tungsten and aluminum elemental powders with composition W–20 wt.% Al were mechanical alloyed in high energy planetary ball mill. Structural and morphological changes of powder particles after different milling times were studied by X-ray diffractometer, scanning electron microscopy and microhardness measurements. Mechanical alloying of this system led to the formation of W–Al alloy as a result of formation of W/Al layered microstructure having faceted interface between layers. This alloy indicated high microhardness value of about 570 Hv. 相似文献
8.
M. Parvin 《Journal of Materials Science》1981,16(7):1796-1800
Brittle fracture of polycarbonate (PC) caused by thermal pretreatment, is discussed in this paper. Further results on the thickness effect provide added support for the earlier work on this aspect. These results together with the temperature effect on the fracture of polycarbonate give a complete picture of brittle fracture in a tough material. 相似文献
9.
Various lines of atomic fluorine laser have been studied over a wide pressure range for determination of the relative intensity of each pressure-dependent line. In this investigation, the most probable laser pumping mechanisms have been verified. 相似文献
10.
Bahram Parvin Qing Yang Ju Han Hang Chang Bjorn Rydberg Mary Helen Barcellos-Hoff 《IEEE transactions on image processing》2007,16(3):615-623
Saliency is an important perceptual cue that occurs at different levels of resolution. Important attributes of saliency are symmetry, continuity, and closure. Detection of these attributes is often hindered by noise, variation in scale, and incomplete information. This paper introduces the iterative voting method, which uses oriented kernels for inferring saliency as it relates to symmetry. A unique aspect of the technique is the kernel topography, which is refined and reoriented iteratively. The technique can cluster and group nonconvex perceptual circular symmetries along the radial line of an object's shape. It has an excellent noise immunity and is shown to be tolerant to perturbation in scale. The application of this technique to images obtained through various modes of microscopy is demonstrated. Furthermore, as a case example, the method has been applied to quantify kinetics of nuclear foci formation that are formed by phosphorylation of histone gammaH2AX following ionizing radiation. Iterative voting has been implemented in both 2-D and 3-D for multi image analysis. 相似文献