International Journal of Engineering
Volume:17 Issue: 4, Dec 2004

Water flow in open channels is always subject to the resistance to flow and energy dissipation. For design purposes, one of the needed variables is the hydraulic resistance coefficient. For this mean, the influence of cross-sectional shape together with secondary flow cells and lateral distribution of true boundary shear stress have not yet been fully explored. This paper surveys the number of research work carried out last few decades and highlights effect of cross sectional shape on resistance to flow. A particular emphasis has been focused on a certain v-shaped bottom channel with vertical walls, and its resistance coefficient evaluation. The experimental results show that albeit the channel has a smooth boundary, but the resistance coefficients cannot be applied for this channel. Thedifference may be arisen by the effect of cross sectional shape. A Karman-Prandtl smooth pipe flow type friction formula was then developed for this particular channel shape. It can also be seen that the Darcy-Weisbach friction factor, f, is more sensitive than that of the Manning n.

The run length of cracking furnaces is limited by the formation of coke on the internal skin of the reactor tubes. The reaction mechanism of thermal cracking of hydrocarbons is generally accepted as free-radical chain reactions. On the basis of the plant output data and the insight in the mechanisms for coke formation in pyrolysis reactors, a kinetic model describing the coke formation has been developed. It consists of seven reactions for coke formation assuming that the sources of coke formation are ethylene, propylene, butadiene and benzene, toluene, xylene and styrene. The coking model was combined with a rigorous kinetic model for the pyrolysis of naphtha and a reactor model. The parameters for this model were determined using nonlinear Marquardt optimization method.The sum of squares of the deviations between the calculated and plant data was used as the objective function and minimized by the appropriate choice of the portion of each reaction involved in coke formation. Finally the simulated and plant output results agree in a good accuracy.

Microencapsulation of liquid orange oil as a common flavoring agent in food industries by complex coacervation in a gelatin – gum arabic polymeric wall system was studied. At a fixed ratio of 10% w/v as concentration of the materials used in this study, trend of changes of microencapsulation process variables using different wall polymeric contents along with varying levels of the core to wall ratio were investigated. Distribution pattern of the coacervate particle size showed that more than 70% of the particle with the average diameter of 9.68 mm were reasonably encapsulated in those treatments having core to wall ratio at the level of 1:1 and 1:2 while gelatin to gum arabic content of the wall system were set to be 1:1 and 2:1 ratio, respectively. The yield of the process as ratio of the amount of coacervate microcapsules produced to the amount of materials initially present in the emulsion was highest (69%) for the treatment described. Moreover, the release and swelling data have been analyzed in terms of the generalized equation Mt/M∞=ktn applicable for swellable controlled release systems. The results obtained were discussed on the basis of the release rate constant k, and diffusional exponent n.

This paper describes the testing of Profiled Steel Sheet Dry Board (PSSDB) load bearing wall system. Experimental tests were conducted on various PSSDB wall samples, with and without infill materials to study its effect on the PSSDB load bearing wall performance. A proprietary profiled steel sheet, Ajiya Cliplock (0.48 mm thick) attached to Cemboard (10 mm thick) on one side, and Cemplank (10 mm thick) on the other side, via self drilling, self tapping screws spaced at 200 mm centre to centre were used for the tests. The height of the tested panels was all fixed at 3 metres. Results show that the ultimate loads at failure were between 28 kN to 45 kN, and between 158 kN to 182 kN for panels without and with infill materials respectively. Panels filled with polystyrene mortar show better axial load performance than panels without infill materials.

This paper is an endeavor to quantify the concept of sustainable transportation. The prevailing idea in the context of sustainable development (SD) emphasizes on the reduction of transportation demand in order to reduce the environmental and social consequences of it. Nevertheless, in the current paper using a measure for SD, and based on the conformity of the growths of all sectors with transportation supply and demand, the countries are comparatively studied. The measure, elasticity, for each two variables indicates the extent to which those two variables have been changing consistently. Indeed the elasticity values are measures of a “harmonic development“representing sustainability. The database consisted of national variables in transportation, economic, social and environmental categories for 128 countries in the period of 1980 to 1995. The study shed some light on the SD of transportation supply and demand, reflecting the harmony of social, environmental and economic development with respect to transportation supply and demand development. Using individual elasticity, composite sustainability indices were suggested. For comparative appraisal, country groupings were developed. The sustainability appraisal showed interesting patterns of within and between group similarities and differences. The study confirmed the significance of transportation supply and demand balancing and sustainability challenges of the 21st century. The methodology may be applied to any other time and geographic scope for addressing pertinent issues for balancing and SD of transportation systems.

The array factor (sidelobe level, SLL) of a linear array is optimized using modified continuous genetic algorithms in this work. The amplitudes and phases of the currents as well as the separation of the antennas are all taken as variables to be controlled. The results of the design using modified GA versions are compared with other methods. Two design problems were studied using several continuous modified GA versions and the results are presented as several plots. As a final example, the design specifications for an array with 200 elements are given. The effectiveness and advantages of the proposed modified GA versions are outlined.

In the design of a cellular manufacturing system (CMS), one of the important problems is the cell formation in the form of machine grouping and parts family. This paper investigates an allocation of parts to common and specific cells; in such a way that each common cell is able to process all required parts. Further, this paper presents a mathematical programming model comprising such constraints as available time for common and special cells in each time horizon, and such variables as excess time required by each cell to process parts in each period. The objective of the model is to minimize the total tardiness in production of goods and sum of idle times of machines in each cell. To obtain good solutions, a simulated annealing (SA) method has been used. To verify the quality and efficiency of the SA algorithm, a number of test problems with different sizes are solved to show the efficiency of the proposed algorithm. Finally, results are compared with solutions obtained by Lingo 6 in terms of objective function values and computational time.

Considering a kinematical velocity admissible field, the upper bound method has beenused for predicting the amount of pressure in hydroforming of sheet metals. The effects of workhardening, friction and blank size have been considered in pressure prediction. Also the effect ofsheet thickness variation has been considered in the present work formulations. The relation betweenpressure and punch stroke has been obtained and optimized by changing the selective parameters inthe velocity components. The results for cylindrical and hemispheric parts have been obtained andcompared with the published experimental results. The effects of work hardening, friction and blanksize on hydroforming pressure have been examined on an elliptical part. Good agreement was foundbetween the experimental and numerical results.

An extensive experimental investigation to study the flow structure over the wing of a fighter type configuration model has been conducted. The model used for this study was similar to the High Alpha Research Vehicle (HARV) that has been used in various European research centers for studying its force and moment characteristics. Tests were conducted at two subsonic speeds and at low to moderate angle of attack. The wing surface pressure distribution and velocity profiles at various angles of attack were measured. This investigation also included suction effects on the wing surface pressure signature. Smoke and tufts were used to visualize the flow over the wing. The results indicate formation of a relatively weak vortex over the wing surface at low angle of attack. As alpha increases, this vortex widens, covering a large portion of the wing, disappearing at moderate angle of attack. Suction affects surface pressure distribution at low to moderate angle of attack, while its effect is reduced at high alpha. It also modifies the velocity profile shape near the surface of the wing.