Numerical calculations of the effect of moisture content and moisture flow on ionic multi-species diffusion in the pore solution of porous materials

A method to analyse and calculate concentration profiles of different types of ions in the pore solution of porous materials such as concrete subjected to external wetting and drying is described. The equations in use have a solid theoretical meaning and are derived from a porous media technique, which is a special branch of the more general mixture theory. The effect of chemical action is ignored, making the presented model suitable to be implemented into codes dealing solely with chemical equilibrium.     

The ETSI computation model: a tool for transmission planning oftelephone networks

This article deals with the ETSI computation model-the E-model-for evaluating speech communication quality in telephone networks. The reasons why such models are of interest for transmission planning of modern networks and the various subjective tests and customer surveys that must form the basis for the computation algorithms are discussed. Then a survey is given of models that are described in the ITU's documents. The structure of the new E-model and the various considerations taken in its development and verification are also discussed. Results from application of the E-model on typical connections agree well with results from other models and from published subjective tests. In particular, impairments caused by low-bit-rate codecs can be quite well predicted by the model, better than by the hitherto used methodology of “quantizing distortion units.” The E-model has also been used in the process of updating some of the ITU-T C-series Recommendations on transmission planning     

Moving from business to technology with service-based processes

In most organizations, business process realizations must be aligned with existing systems, which can impose specific requirements. Currently, however, there is no way to track the alignment between business processes and corresponding technical implementations. The authors' proposed framework offers a systematic way to classify and assess technical realizations of business processes.     

Residual stresses in fibre- and whisker-reinforced aluminium alloys during thermal cycling measured by X-ray diffraction

Residual stresses have been determined using X-ray diffraction in two different metal matrix composites, viz. a squeeze-cast Al-2%Mg matrix with 10, 20 or 26 vol.% Al₂O₃ fibres and an extruded AA 6061 alloy with 25 vol.% SiC whiskers. The composites have been studied after thermal cycling between 240 or 250 °C and room temperature succeeded in some cases by quenching to liquid nitrogen temperature. On the squeeze-cast composite, stresses were measured at room temperature and in situ at 240 °C. X-ray stress determinations were compared with the stress values calculated by a modified Eshelby model for equivalent inclusions. By the model, the stresses can be accurately predicted for both composite systems. Thermally induced plastic relaxation reduces the residual stresses. The degree of reduction depends on the reinforcement volume fraction, the difference in coefficient of thermal expansion between the phases and the magnitude of the temperature drop. At elevated temperature the stresses are less responsive to reiterated quenching and heating.     

On nested convolutional codes and their application to woven codes

Nested convolutional codes are a set of convolutional codes that is derived from a given generator matrix. The structural properties of nested convolutional codes and nested generator matrices are studied. A method to construct the set of all minimal (rational) generator matrices of a given convolutional code is presented. As an example, two different sets of nested convolutional codes are derived from two equivalent minimal generator matrices. The significant difference in their free-distance profiles emphasizes the importance of being careful when selecting the generator matrices that determine the nested convolutional codes. As an application of nested convolutional codes, woven codes with outer warp, and inner nested convolutional codes are considered. The free-distance profile of the inner generator matrix is shown to be an important design tool.     

On the influence of a martensitic transformation in the substrate on a hard coating

Cobalt was coated with TiC in a chemical vapour deposition process. The strain arising from the f.c.c.→h.c.p. transformation in cobalt imposes stresses in the coating. These stresses cause cracks in the coating perpendicular to the substrate-coating interface.The perpendicular cracks have a stress-concentrating effect on microvoids in the interface. A fracture mechanical estimation shows that the adherence of the coating under shear stress loading is markedly influenced by the cracks caused by the martensitic transformation.     

Two 16-state, rate R=2/4 trellis codes whose free distances meetthe Heller bound

For rate R=1/2 convolutional codes with 16 states there exists a gap between Heller's (1968) upper bound on the free distance and its optimal value. This article reports on the construction of 16-state, binary, rate R=2/4 nonlinear trellis and convolutional codes having d _free=8; a free distance that meets the Heller upper bound. The nonlinear trellis code is constructed from a 16-state, rate R=1/2 convolutional code over Z₄ using the Gray map to obtain a binary code. Both convolutional codes are obtained by computer search. Systematic feedback encoders for both codes are potential candidates for use in combination with iterative decoding. Regarded as modulation codes for 4-PSK, these codes have free squared Euclidean distance d_{E, free}²=16     

The two-exon gene of the human forkhead transcription factor FREAC-2 (FKHL6) is located at 6p25.3

Subcutaneous metastases from clear cell endometrial carcinoma are an uncommon event and tumor implantations are rarely found with diagnostic imaging techniques. The nodular form is the most frequent type of subcutaneous metastasis from genital system tumors, even though plaque-like and infiltrative forms have also been reported. We report the first case of subcutaneous metastasis from clear cell endometrial carcinoma whose progression from the early nodular to the lymphangitic infiltrative form was studied with computed tomography (CT). Differential diagnostic problems are discussed.     

The detailed structure of delamination fracture surfaces in graphite/epoxy laminates

Delamination fracture surfaces of angle-ply graphite/epoxy specimens failed in tension were studied in the SEM. The fracture surfaces contain resin-rich and resin-poor areas, with the former showing imprints from fibres while the latter show debonded fibres. A delamination crack propagates in the outer parts of the plies adjacent to the resin-rich interlaminar region and alternates from one ply to the adjacent ply and back as it propagates. The serrations formed in between fibres in the outermost parts of plies are tilted. The sense of the tilt is in agreement with the direction of the major tensile principal stress. The delamination is suggested to proceed in steps including debonding of fibres, crack opening by the major principal tensile stress and linking together of these fractures.