Fatigue growth of multiple-cracks near a row of fastener-holes in a fuselage lap-joint

The fatigue growth of multiple cracks, of arbitrary lengths, emanating from a row of fastener holes in a bonded, riveted, lap joint in a pressurized aircraft fuselage is studied. The effects of residual stresses due to a rivet misfit, and of plastic deformation near the hole, are included. A Schwartz-Neumann alternating method which uses the analytical solution for a row of multiple colinear cracks in an infinite sheet (the crack-faces being subject to arbitrary tractions), is developed to analyze this MSD problem on a personal computer. It is found that for a range of crack lengths, a phenomena wherein the shorter cracks may grow faster than longer cracks may exist.     

Microwave induced plasma processing of nuclear waste calcines

Microwave induced plasma processing was used to sinter synthetic Idaho Chemical Processing Plant (ICPP) alumina and zirconia based high level nuclear waste calcines in a nitrogen atmosphere. The microwave densification behaviour of these nuclear waste calcines was observed parallel with identification of the phases formed after sintering. Sintered densities of > 3.20 g cm^–3 were obtained within 10 min of microwave sintering of pure calcines. Glass frit containing calcines showed lower sintering densities (< 2.0 g cm^–3) due to reactions between the frit and volatile substances in both zirconia based and alumina based calcines; prior removal of frit volatiles increased the sintered density. Phases formed in the microwave sintered calcines were identified by X-ray diffraction.     

Semiconductor optical amplifier for CWDM operating over 1540-1620 nm

A semiconductor optical amplifier was developed for coarse wavelength-division-multiplexing (CWDM) operating over 1540-1620 nm (C-L band). A unique quantum-well structure was designed to meet the requirements for the CWDM operation such as wide bandwidth, low polarization-dependent gain, and high-saturation power at the short wavelength end of the band (1540 nm). Over the band, 24-dB maximum chip gain was obtained with less than 4.3-dB gain flatness and more than 14.6-dBm saturation power.     

2.488 Gb/s-318 km repeaterless transmission using erbium-dopedfiber amplifiers in a direct-detection system

The authors have achieved a 2.488 Gb/s, 318 km repeaterless transmission without any fiber dispersion penalty through a nondispersion-shifted fiber in a direct detection system. The system was loss limited with a T-R power budget of 57 dB. Three key components enabled the authors to achieve this result: (1) a Ti:LiNbO₃ external amplitude modulator enabling a dispersion-free transmission, (2) erbium-doped fiber amplifiers increasing the transmitting power to +16 dBm, and (3) an erbium-doped fiber preamplifier enabling a high-receiver sensitivity of -4.1 dBm for 10^-9 BER. To the author's knowledge, this result is the longest repeaterless transmission span length ever reported for direct detection at this bit rate. From the experimental results and a theoretical model, the authors identified the sources of the receiver sensitivity degradation from the quantum limit (-48.6 dBm) and estimated the practically achievable receiver sensitivity of ~-44 dBm (~-124 photons/bit) for 2.5 Gb/s optical preamplifier detection     

Pseudorandomness of Basic Structures in the Block Cipher KASUMI

The notion of pseudorandomness is the theoretical foundation on which to consider the soundness of a basic structure used in some block ciphers. We examine the pseudorandomness of the block cipher KASUMI, which will be used in the next‐generation cellular phones. First, we prove that the four‐round unbalanced MISTY‐type transformation is pseudorandom in order to illustrate the pseudorandomness of the inside round function FI of KASUMI under an adaptive distinguisher model. Second, we show that the three‐round KASUMI‐like structure is not pseudorandom but the four‐round KASUMI‐like structure is pseudorandom under a non‐adaptive distinguisher model.     

Crystalline and viscoelastic properties of branched polyethylenes synthesized using bidentate nickel (II) catalyst

In this work, five branched polyethylenes with different branching units were synthesized using bidentate nickel (II) catalyst containing -diimine ligands. For comparison, one linear polyethylene was also prepared using tridentate iron (II) catalyst containing -diimine ligand. The crystalline structure of the polyethylenes was investigated using X-ray diffraction (XRD) and polarized optical microscope. The crystalline properties were also measured by differential scanning calorimeter (DSC). Viscoelastic properties of the polyethylenes were investigated using rheometric dynamic analyzer. The DSC and XRD results showed that highly branched polyethylenes exhibit no melting points and no predominating crystalline forms, while the linear polyethylene exhibits clear orthorhombic (110) and (200) reflections on XRD pattern and a clear melting point at 118 °C. The viscoelastic properties of the branched polyethylenes were very complicated due to the combined effect of the molecular weight difference and the degree of chain branching as well as the branching structure.     

Master sintering curve concepts as applied to the sintering of molybdenum

Sintering experiments with various molybdenum powders are rationalized using a master sintering curve concept that collapses density, grain size, or other parameters onto a single curve. In this case, the integral work of sintering is developed and customized for different green densities. Construction of the master sintering curve is described to show how the curve can be normalized with respect to green density effects. Various grades of molybdenum for metal injection molding and die compaction are included in the analysis, processed over a range of heating cycles. Die-compacted samples of varying green densities are used to illustrate the efficacy of the new, normalized master sintering curve concept. Sintering cycle optimization is one possible outcome from this analysis.     

Surface characteristics of fluorine-modified PAN-based carbon fibers

Different fluorination methods were applied to modify the surface properties of carbon fibers. The relationship between the degree of fluorination and the physicochemical properties of carbon fibers was studied using a combination of mechanical tests, elemental analysis (EA), X-ray photoelectron spectrometry (XPS), and X-ray diffraction (XRD). EA and XPS analyses of fluorinated carbon fibers showed that treatment with mixtures of F₂/O₂ introduced a much higher fluorine concentration than that with F₂ only. However, XRD analysis showed that there was no increase in the interlayer distance, due to the mild fluorination condition applied. Consequently, the oxyfluorination was one of the more effective methods to increase surface polarity of carbon fibers, which probably played an important role in improving the tensile properties of the fibers in the epoxy resin system.     

Error Concealment Based on Semantic Prioritization with Hardware‐Based Face Tracking

With video compression standards such as MPEG‐4, a transmission error happens in a video‐packet basis, rather than in a macroblock basis. In this context, we propose a semantic error prioritization method that determines the size of a video packet based on the importance of its contents. A video packet length is made to be short for an important area such as a facial area in order to reduce the possibility of error accumulation. To facilitate the semantic error prioritization, an efficient hardware algorithm for face tracking is proposed. The increase of hardware complexity is minimal because a motion estimation engine is efficiently re‐used for face tracking. Experimental results demonstrate that the facial area is well protected with the proposed scheme.