Layer model for long-term deflection analysis of?cracked?reinforced concrete bending members

A numerical technique has been proposed for the long-term deformation analysis of reinforced concrete members subjected to a bending moment. The technique based on the layer approach in a simple and rational way deals with such complex issues as concrete cracking and tension-stiffening as well as creep and shrinkage. The approach uses the material stress-strain relationships for compressive concrete, cracked tensile concrete and steel. Such effects as linear and nonlinear creep, cracking, tension-stiffening as well as the reduction in concrete tension strength due to sustained loading have been taken into account. The shrinkage effect has been modeled by means of adequate actions of axial force and bending moment. A statistical deflection calculation analysis has been carried out for 322 experimental reinforced concrete beams reported in the literature. The comparative analysis of the experimental and the modeling results has shown that the proposed technique has well captured the time-deflection behavior of reinforced concrete flexural members. The results of the predictions by ACI 318 and Eurocode 2 design codes have been also discussed.     

Intrinsic instability of flame–acoustic coupling

This paper shows that a flame can be an intrinsically unstable acoustic element. The finding is clarified in the framework of an acoustic network model, where the flame is described by an acoustic scattering matrix. The instability of the flame acoustic coupling is shown to become dominating in the limit of no acoustic reflections. This is in contrast to classical standing-wave thermoacoustic modes, which originate from the positive feedback loop between system acoustics and the flame. These findings imply that the effectiveness of passive thermoacoustic damping devices is limited by the intrinsic stability properties of the flame.     

EELS microanalysis of polycrystalline silicon thin films for solar cells grown at low temperatures

The aim of this work is the quantitative chemical analysis of polycrystalline silicon thin films grown on glass substrates at temperatures <600°C by means of transmission electron microscopy (TEM) and electron energy-loss spectrometry (EELS). Specimens produced with two different methods were investigated. We found significant differences in grain size and morphology, as well as in the distribution of oxygen. A surprisingly high amount of Ba diffusion from the subtrate was detected.     

Photo-induced transformations in amorphous chalcogenide nano-multilayers

Photo-stimulated interdiffusion in a-Se/As₂S₃ amorphous chalcogenide nano-multilayers (ANML) is known as a useful method for amplitude-phase optical relief formation besides the known amorphous–amorphous or amorphous–crystalline photo-induced structural transformations (PST) in homogeneous chalcogenide layers, but it has a relatively narrow sensitivity spectral range and small amplitude modulation. Experimental evidences of improvement of optical recording processes were obtained in Te-, Bi-, Sb-containing nano-layered structures based on As₂S₃ matrix. The influence of nano-structuring and combination of components on the sensitivity, type of the recorded relief is discussed.     

Spin versus fair speak in food labelling: A matter of taste?

The article sheds new light on sensory elements in legal cases concerning misleading food labelling. It presents the findings of a qualitative review of 821 cases on misleading food labelling registered in 2002–2007 by the Danish food authorities. The cases show that sensory tends to be backgrounded by other arguments more easily verbalized. A taxonomy of the sensory dimensions of the cases is set up and different sensory aspects are analyzed in order to establish to what the extent and how sensory variables can be integrated into experimental setups for testing the misleading potential of food naming and labelling solutions with a view to promoting “fair speak” principles for in-store food-to-consumer communication. The study is part of the cross-disciplinary research project “Spin or fair speak – when foods talk” which aims at providing new knowledge, tools, and experimental evidence for self-regulation, public control, and innovation in food naming and labelling.     

Inductive Learning with a Computational Network

This paper introduces a computational network which combines heterogeneous rule-extraction algorithms for intelligent data analysis. Combining induction programs may alleviate the possible negative effects of data set representation and individual program's influences, such as inductive bias. The application of the computational network to a diabetes data set shows that, when combining the various programs, an increase in rule set accuracy and comprehensibility are obtained.     

Structural Changes during Milling of Silicon Carbide

The kinetics of milling and structural changes during milling of commercial silicon carbide powder in a ball mill lined with hard alloy are studied. Data are provided for the specific surface, x-ray patterns, and infrared spectra. It is shown that milling kinetics are described best of all by an exponential relationship and that milling of silicon carbide powder is accompanied by changes in polytype composition. The x-ray patterns and infrared spectra obtained make it possible to assume that during milling the 15R polytype content in the powder composition decreases while the content of structures with less layering (the 4H polytype and -SiC) increases; in this case the number of absorption bands in the infrared spectra decreases.     

Development and optimization of a mid-infrared hollow waveguide gas sensor combined with a supported capillary membrane sampler

A gas sensor for application in water analysis was developed by combination of a mid-infrared (MIR) hollow waveguide with a Fourier transform infrared (FT-IR) spectrometer and coupling of the hollow waveguide gas sensor module to a supported capillary membrane sampler (SCMS) for continuous liquid-gas extraction. Different hollow waveguides have been characterized in this study for developing an optimized optical configuration. Analysis of industrially relevant compounds has been performed, investigating chlorinated hydrocarbons (CHCs), such as dichloromethane and chloroform, representing highly volatile analytes, and 1,4-dioxane as an example of target compounds with low volatility. The suitability of this spectroscopic IR sensing system for industrial applications is demonstrated under simulated real-world conditions with limits of detection in the ppb (v/v) and ppm (v/v) concentration range for CHCs and 1,4-dioxane, respectively.     

Towards dynamics of controlled multibody systems with magnetostrictive transducers

The paper addresses mechatronic issue of multibody systems comprising giant magnetostrictive material based transducers (sensors and/or actuators). Interaction between dynamics and control in multibody system with smart material based transducers makes it possible to change system properties and functionality substantially as a response to applied electric, magnetic or temperature fields. To use this interaction in an optimal way, the proper mathematical models of controlled electro-magneto-elastic multibody systems need to be developed. In the paper, a general mathematical model of multibody systems with magnetostrictive transducers is presented. The model consists of the constitutive equations of magnetoelastic behavior of transducers, standard formulae of electromagnetism for induced voltage and current in the pick-up coil due to variation of magnetic field intensity, and finally, the equations of motion of multibody system itself. The last one can be derived using one of the well-known multibody dynamics formalisms. General model has been developed in detail for linearized dynamics of magnetostrictive transducers and implemented virtually for two practically important cases of interaction of hosting multibody system with transducers, namely for systems with displacement driven transducers and for systems with force driven transducers. Physical prototype of magnetostrictive transducer and test rig (hosting multibody system) have been built and used successfully for verification of developed models.     

A comparative numerical study of hybrid-stabilized argon–water electric arc

The paper presents numerical simulations of the discharge and the near-outlet regions of the hybrid-stabilized argon–water electric arc. Two different numerical methods for solving the set of conservative equations for the continuity, momentum and energy have been applied. The major difference between the results using the two methods occurs in the temperature distribution in arc fringes within the discharge chamber. This fact influences the potential drop, overpressure, reabsorption of radiation and arc efficiency. It is shown that the radial profiles of temperature at the exit nozzle are less influenced by different temperature distribution within the discharge chamber. Comparison with chosen experimental temperature profiles shows very good agreement.