International Journal of Engineering
Year:2004 | Volume:17 | Issue:1 (TRANSACTIONS B: APPLICATIONS)|Papers Count:9

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 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.: h=h__p#f__p/#F could be estimated, the ‎Stagewise forward mixing with coalescence and redispersion model will predict the ‎column height and efficiency with the acceptable accuracy, (2) The Stagewise ‎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 te 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.‏

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 on 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 coordinated 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 sub-process 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.‏

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 suing 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 tan#d values indicating less energy loss when the ‎compatibilizer was present‏.‏