Shear strengthening of old concrete beams

In our March-April issue last year, the author described work at the Czech Technical University in Prague on the use of epoxy resins to apply new flat reinforcement to old concrete beams in order to enhance or prolong their service life. Here, some further test results and general conclusions are presented on the application of this technique to shear strengthening. The author is Associate Professor of Civil Engineering at the University.     

Semantically-enabled service oriented architecture : concepts, technology and application

Semantically enabled service-oriented architecture focused on principles of service orientation, semantic modeling, intelligent and automated integration defines grounds for a cutting-edge technology which enables new means to integration of services, more adaptive to changes in business requirements which occur over systems’ lifetime. We define the architecture starting from a global perspective and through Web service modeling ontology as its semantic service model we narrow down to its services, processes and technology we use for the reference implementation. On a B2B integration scenario we demonstrate several aspects of the architecture and further describe the evaluation of the implementation according to a community-agreed standard evaluation methodology for semantic-based systems.     

Search for Fundamental Articles in Economics

The aim of this article is to demonstrate on the scientific field "economics" the search for fundamental articles.Co-word analysis and co-citation analysis enable to visualize the structure of a scientific field on the maps of science. Then we can find the fundamental themes on the maps. After finding the articles belonging to these fundamental themes we can discuss the fundamentality of the formers, too.     

Relationship between employee involvement and lean manufacturing and its effect on performance in a rigid continuous process industry

This research aims to empirically test the effect of employee involvement on lean manufacturing (LM), and the effect of LM on production outcomes. Employee involvement is operationalised through four related variables: empowerment, training, contingent remuneration and communication. The effects are tested by recording management perceptions in a different industrial sector from those usually studied in previous research – ceramic manufacturers, a highly competitive and internationally successful sector. We obtained data from 101 ceramic tile plants (64% of response rate) in the Valencia region of Spain. This approach is developed using a statistical method called partial least squares. All paths are significant except for contingent remuneration; specifically, relationships were found between empowerment, training, communication and LM, and between LM and performance.     

Interparticle Collision of Particle Composites—Finite and Discrete Element Simulations

Three different cases of interparticle collisions were simulated to observe the fragmentation mechanisms of composite particles. It was found that the cracking mechanism in interparticle collisions is different from that observed in particle-wall collisions. By means of DEM simulations, it was observed that the primary interparticle bonds break in both tension and shear. Depending on the type of interparticle collisions, cracks and fragments are generated. In general, finer fragments are generated around the impact site of the particles and are surrounded by larger fragments. From DEM simulations, it was found for the most part that the impacting particles exhibit more damage than the stationary particles. The symmetrical loading showed almost the same amount of damage to both types of particles. The discontinuous nature of the material and the unsymmetrical loading caused unsymmetrical damages (crack patterns). In unsymmetrical loadings, the impacting particle was more damaged and had more cracks than the stationary particle.     

Assessment of Mechanical Properties of Cohesive Particulate Solids. Part 2: Powder Flow Criteria

The fundamentals of cohesive particulate solids' consolidation and flow properties using a reasonable combination of particle and continuum mechanics by means of micro/macrotransition of the "characteristic particle contact" are explained. The adhesion force models of Tomas (2001a) are used to derive the stationary, instantaneous T S1 time yield loci and consolidation loci. Next, the uniaxial compressive strength σ c ( σ 1 ), effective angle of internal friction } e ( σ 1 ), and bulk density 𝜌 b ( σ 1 ) are obtained as powder constitutive functions. The approach has been shown to be effective for the data evaluation of cohesive powder flow properties, like a very cohesive titania nanopowder (surface diameter d s = 200 nm, solid density 𝜌 s = 3870kg/m 3 ) with the fit r 2 xy > 0.95. Finally, these models in combination with accurate shear cell test results are used as constitutive functions for computer-aided silo design for reliable flow.     

Numerical implementation of the S-matrix algorithm for modeling of relief diffraction gratings

A new numerical implementation is developed to calculate the diffraction efficiency of relief diffraction gratings. In the new formulation, vectors containing the expansion coefficients of electric and magnetic fields on boundaries of the grating layer are expressed by additional constants. An S-matrix algorithm has been systematically described in detail and adapted to a simple matrix form. This implementation is suitable for the study of optical characteristics of periodic structures by using modern object-oriented programming languages and different standard mathematical software. The modeling program has been developed on the basis of this numerical implementation and tested by comparison with other commercially available programs and experimental data. Numerical examples are given to show the usefulness of the new implementation.     

Solvent-assisted trypsin digestion of ricin for forensic identification by LC-ESI MS/MS

The castor bean plant (Ricinus communis) is used in large quantities for oil production and is also a common ornamental garden plant. However, the beans contain 1-3% of the highly toxic protein ricin, a type II ribosome-inactivating protein that is covered by the Chemical Weapons Convention, and there have been a number of reports concerning the use, or alleged use, of the toxin in terrorist and criminal activities. In the study reported here, we investigated the potential utility of organic solvent-assisted trypsin digestion of crude extracts containing the closely related toxins ricin or abrin to prepare samples for peptide analysis by liquid chromatography combined with electrospray ionization quadrupole time-of-flight tandem mass spectrometry. Diagnostic tryptic fragments of the toxins were detected and unambiguously identified by this procedure. The sample preparation protocol substantially reduces the sample preparation time, from overnight to an hour, and thus greatly reduces the total time required for analyses, to less than 2 h. Furthermore, the reported procedure leaves the disulfide bonds in the protein intact. This is highly relevant in the context of the Chemical Weapons Convention, since the disulfide bond connecting the two chains of ricin indicates the presence of an intact toxin and provides additional forensic evidence for the analytical results.     

The effect of powder characteristics on pressure sensitivity of powder injection moulding compounds

Pressure effect on the rheological behaviour of powder-polymer compounds intended for powder injection moulding was determined. A single-piston capillary rheometer modified by addition of a second chamber with a restricting needle valve generating backpressure increasing the pressure in the melted material during the flow through the die was employed to determine pressure sensitivity coefficients. The results obtained for three compounds varying in the characteristics of powders used confirmed that compounds at the loading level close to the maximum packing are more sensitive to pressure than polymer binder. It is shown that pressure sensitivity coefficients of these materials are strongly dependent on powder characteristics — particle size and particle size distribution. The highest coefficient (32.9 GPa⁻¹) was found for compound containing broad particle size distributed powder having a perceptible portion of small particles.