International Journal of Engineering
Volume:23 Issue: 2, Apr 2010

This paper describes an attempt to shed some light on road safety in Asia Pacific regionby characterizing and assessing its road accidents. The relevant national road accident data were extracted from centralized data sources of international agencies. Due to data incompleteness and missing values, 21 Asia Pacific countries, presenting more than half of the world’s population, were selected for detailed analysis. The study database consisted of 7 variables, covering years 1980 and 1995. The univariate and multivariate statistical analyses for the selected countries showed interesting results and relations for the selected variables. Accident rates, reflecting road accident risk and intensity, were developed, evaluated and modelled. Deploying multi-criteria analysis techniques suchas data envelopment analysis, DEA, provided appropriate bases for cross-sectional appraisal and target setting. As safety is one of the aspects of sustainable transportation, arc elasticity of road accident variables with respect to demographic, economic and road transportation supply variables through time were developed and analysed. Based on the developed elasticities, a composite road safety sustainability index was suggested. The appraisal of road accident for the Asia Pacific countries suggested that road accident has posed a creeping public safety crisis for the region. The study showed that the magnitude of road accident problem varied considerably among countries. The study offers the methodology and conclusions of a comparative macroscopic road accident appraisal for the Asia Pacific region.

The utilization of unbounded external reinforcing bars is one of the strengthening methods used after loading stage and before failure. The method has been used in different forms to strengthen members of reinforced concrete structures. To investigate the effect of utilization of post-tensioned reinforcing bars in this method of strengthening, a number of reinforced concrete beams was tested. Strengthening was carried out by attaching external bars on both outside faces of the beam in the level ofinternal flexural tension reinforcement. The behavior of strengthened beams was then studied both by experiment and modeling using ANSYS finite element structural software. In post-tensioning of external reinforcing bars, hydraulic jack was used. The results showed that this method of strengthening has increased the flexural capacity, and decreased the ductility of the beams. It was also shown that the increase in flexural strength caused by the utilization of unbounded external post-tensioned reinforcingbars was in reverse proportion with the percentage of internal flexural tension reinforcement. It was also concluded that the method is very effective for beams with lower percentages of internal flexural tension reinforcement.

In order to study the effect of R2O/Al2O3 (where R=Na or K), SiO2/Al2O3, Na2O/K2O and H2O/R2O molar ratios on the compressive strength (CS) of Metakaolin base geopolymers, more than forty data were gathered from literature. To increase the number of data, some experiments were also designed. The resulted data were utilized to train and test the three layer artificial neural network (ANN). Bayesian regularization method and Early Stopping methods with back propagation algorithm were applied as training algorithm. Good validation for CS was resulted due to the inhibition of overfitting problems with the applied training algorithm. The results showed that optimized condition of SiO2/Al2O3, R2O/Al2O3, Na2O/K2O and H2O/R2O ratios to achieve high CSshould be 3.6-3.8, 1.0-1.2, 0.6-1 and 10-11, respectively. These results are in agreement with probable mechanism of geopolymerization.

The analysis of viscoelastic materials is one of the most important subjects in engineeringstructures. Several works have been so far made for the integral equation methods to viscoelastic problems. From the basic assumptions of viscoelastic constitutive equations and weighted residual techniques, a simple but effective Boundary Element (BE) formulation is developed for the Kelvin viscoelastic solid models. This formulation needs only Kelvin’s fundamental solution of isotropic elastostatics with material constants prescribed as explicit functions of time. It is able to solve the quasistatic problems with any load time-dependence and boundary conditions. A system of timedependentequations is derived by imposing the convenient approximations and adopting the kinematical relations for strain rates. This approach avoids the use of relaxation functions and mathematical transformations. The main feature of the proposed formulation is the absence of domain discretizations, which simplifies the treatment of problems involving infinite domains. A computer code has been developed in the programming environment of MATLAB software. At the end of this paper, two numerical examples have been provided to validate this formulation.

Bluff body calculation was accelerated by using a special-purpose computer,MDGRAPE-2, that was exclusively designed for molecular dynamics simulations. The three main issues were solved regarding the implementation of the MDGRAPE-2 on vortex methods. These issues were the efficient calculation of the Biot-Savart and stretching equation, the optimization of the table domain, and the round-off error caused by the partially single precision calculation in the MDGRAPE-2. Finally this technique was applied to calculation of flow around a circular cylinder. The drag and lift coefficient was investigated to check the validity of the proposed method.

A quad inserted into a turbulent boundary layer of a flat plate and its effect on averageheat transfer and the friction coefficient is studied. To optimize this effect, the edge sizes and distance of the quad from the flat plate are continually modified. In each case, simultaneously the heat transfer enhancement and reduction in skin friction are analyzed. For optimization, the genetic algorithm technique is employed and the results of each step of progress studied by following the Pareto curves. Physical domain is divided into control volumes, over which flow equations are discretized. To deal with the turbulence, several turbulence schemes are examined and appearance of flow features andstability in hard environments are monitored. The turbulence model proved to givereliable solutions and stability to all the 1,600 cases under consideration. Based on the Pareto curve and with no single exceptions of the cases studied, results show that as the heat transfer coefficient rises, the skin friction falls simultaneously; in other words, there is an inverse relation between heat transfer enhancement and skin friction. Conclusion also made that the rate of heat transfer enhancement is more sensitive to modification on small area quads than those of large ones. Since the experimental validation of too many cases was impractical, random comparison between some numerical results and wind tunnel experiments is performed. The comparison showed that the numerical results are strongly in agreement with the experiments.

In this paper, we intend to focus on the sensor network applications in firefighting. Adistributed algorithm is developed for the sensor network to guide firefighters through a burning area. The sensor network models the danger of the area under coverage as obstacles, and has the property to adapt itself against possible changes. The protocol developed, will integrate the artificial potential field of the sensors with the information of the intended place of moving firefighter so that it guides the firefighter step by step through the sensor network by choosing the safest path in dangerous zones. This protocol is simulated by Visual-Sense and the simulation results are available.