International Journal of Engineering
Volume:17 Issue: 1, Apr 2004

Measurement of stress transients generated by a 400ns pulsed HF laser in an infrared fluoride glass fiber has been made using fast time – response piezoelectric film transducer. Acoustic signals up to 12 mV with frequencies ranging in megahertz generated by 21 mJ laser pulse when passed through the fiber axis in the linear region. It is shown that useful information such as onset of non - linear behavior of the fiber can be gained from such measurements, which in turn can be used as a means of monitoring the quality of fiber surface during an operation.

Stagewise forward mixing model considering coalescence and redispersion of drops was used to predict the performance of Rotating Disc Liquid-Liquid Extraction Contactors. Experimental data previously obtained in two RDC columns of 7.62cm diameter, 73.6cm height and 21.9cm diameter, 150cm height were used to evaluate the model predictions. Drop-side mass transfer coefficients were predicted applying Handlos-Baron drop model and Olney''s model was used to predict drop velocities. According to the results obtained the followings could be concluded: (1) If the height of coalescence and redispersion i.e.: could be estimated, the stage wise forward mixing with coalescence and redispersion model will predict the column height and efficiency with the acceptable accuracy, (2) The stage wise modeling predictions are highly dependent on the number of stages used when the number of stages is less than 10 and (3) Application of continuous phase mass transfer and axial dispersion coefficients (kc and Ec) obtained from the solute concentration profile along the column height will predict the column performance more accurately than the Calderbank and Moo-Young (for kc) and Kumar-Hartland (for Ec) correlations.

Frequency response diagrams of a system include detailed and recognizable information about the structural and parameter effects of the transfer function model of the system. The information are qualitatively and quantitatively obtainable from simultaneous consideration of amplitude ratio and phase information. In this paper, some rules and relationships are presented for making use of frequency response information in order to identify the structure of rational and irrational models in a heuristic manner. Estimation of the values of the parameters are also accomplished in a graphical trial and error procedure. As an example, the heuristic method was applied for identifying the simplified model of a rotary cement kiln from the frequency response information of the analytically derived model of the system. The analytical model of the kiln, used in this paper, was obtained elsewere in a detailed procedure with some assumptions and by using initial and boundary conditions. Results obtained from identification of the simplified model for rotary cement kiln not only reveal the application of the heuristic method for model identification, but also demonstrate the appearance of unstable poles and zeros in the model of the system. Keywords Heuristic Identification, Model Structure, Irrational Transfer Function, Distributed Parameter, Rotary Cement Kiln, Limited-Delay-Resonance, Unlimited-Delay-Resonance

Cementitious matrices are the fragile materials that possess a low tensile strength. The addition of fibers randomly distributed in these matrices improves their resistance to cracking, substantially. However, the incorporation of fibers into a plain concrete disrupts the granular skeleton and quickly causes problems of mixing as a result of the loss of mixture workability that will be translated into a difficult concrete casting in site. This study was concerned on the one hand with optimizing the fibers reinforced concrete mixes in the fresh state, and on the other hand with assessing the mechanical behavior of this mixture in the hardened state, in order to establish a compromise between the two states. In the first part of this paper, an experimental study of an optimization method of fibers reinforced concrete while taking into account of some parameters related to the matrix e.g. volume of the admixture, volume of incorporated fibers and the volume of water and, cement (W, C) in function of workability time are presented. Finally, test specimens of mixture optimized by this method have been tested in compression and tension due to bending. The results have been compared with those of mixture test specimens optimized by Baron – Lesage method.

Both the cogging and electromagnetic torques depends on the shape of the flux density distribution in the airgap region. A two-dimensional (2-D) analytical method for predicting the open- circuit airgap field distribution in brushless permanent magnet motors, considering the direction of magnetization, i.e., radial or parallel, and the effect of real shape of stator slot-openings is presented in this paper. It involves the solution of the governing field equations in polar coordinates in airgap and magnet regions. This method uses a new 2-D relative permeance function. For the comparison purposes, a 2-D finite element (FE) analysis is used for the analysis of a fully-pitched, double-layer windings brushless permanent-magnet (PM) drive. The results obtained by this method are very close to those obtained by FE analysis especially at the corner tips of the tooth.

The final quality and cost of a manufactured product are determined to a large extent by the engineering design of the product and its production process through activities of off-line quality control methods, namely, System Design, Parameter Design and Tolerance Design. However, in the context of most non-industrialized countries, the off-line quality activities of product design and system design of production process design stages are negligible if not absent. Thus, whatever quality control activities there are in these countries should be confined only to conducting parameter (robust) design of manufacturing process design and on-line quality control activities. Out of these two activities, Robust Design is the most economical method as it increases quality and/or reduces costs without imposing any further investment in factors of production. It is in this context that robust design as an optimization method has been used to improve the product quality of cleaning subprocess of beer brewing process of Behnoosh Company in which 358% improvement over the current condition has been achieved.

In this paper we describe the distribution problems faced by one of the largest retailers in the distribution and sale of fast moving consumer goods in the U.K. The paper describes an initial solution method, which is then improved by a novel form of simulated annealing. A computational experiment for the improvement algorithm has been also carried out in order to illustrate the flexibility of the computer programming and to demonstrate how it can be used to address broader management issues.

In this work, the effects of carbon content and manganese sulfide addition on the microstructure and mechanical properties of copper steel parts have been studied. Steel powder mixture containing 2%Cu and different graphite contents with and without MnS additions were compacted, sintered and forged to almost full density. Forged samples, with near theoretical densities, were tested for tensile, hardness, impact and fatigue properties. The microstructures of samples were also studied using optical microscope and scanning electron microscope. It was found that increasing the carbon content did not have any significant effect on fatigue properties of samples, but endurance strength was reduced due to addition of MnS. Furthermore, tensile and yield strength increased by increasing carbon content. Additions of manganese sulfide decreased both tensile and yield strengths but significantly improved the impact energy and elongation of the products.

Abstract In this study, effect of MAPE (maleic anhydride polyethylene) as the compatibilizer on the mechanical properties of wood-flour polyethylene composites has been investigated by using Dynamic Mechanical Analysis (DMA). Composites were made at 25% and 50% by weight fiber contents and 1% and 2% compatibilizer respectively. Controls were also made at the same fiber contents without the compatibilizer. Static mechanical tests including tensile and bending tests were performed. Temperature scans in the range of -110 to +100°C was also conducted. Results indicated improvements in the mechanical properties due to the compatibilizer addition. Storage modulus values were higher in the case of coupled composites especially at 50% fiber loading. Glass transition was hard to detect in all composite systems while increasing fiber content slightly shifted alpha transition to higher temperatures. MAPE had negligible effects on the main transitions but the effect of fiber content on the intensity and temperature of alpha transition seemed to be proportional to the fiber content. Mechanical loss factor spectra showed that at 50% fiber content, the compatibilizer caused a reduction in tanδ values indicating less energy loss when the compatibilizer was present.