Band 3, Heft 1

The privacy of sensitive events observed by a wireless sensor networks (WSN) needs to be protected. Adversaries with the knowledge of sensor deployment and network protocols can infer the location of a sensed event by monitoring the communication from the sensors even when the messages are encrypted. Encryption provides confidentiality; however, the context of the event can used to breach the privacy of sensed objects. An adversary can track the trajectory of a moving object or determine the location of the occurrence of a critical event to breach its privacy. In this paper, we propose ring signature to obfuscate the spatial information. Firstly, the extended region of location of an event of interest as estimated from a sensor communication is presented. Then, the increase in this region of spatial uncertainty due to the effect of ring signature is determined. We observe that ring signature can effectively enhance the region of location uncertainty of a sensed event. As the event of interest can be situated anywhere in the enhanced region of uncertainty, its privacy against local or global adversary is ensured. Both analytical and simulation results show that induced delay and throughput are insignificant with negligible impact on the performance of a WSN.

Novel techniques for laser beam atmospheric extinction measurements, suitable for several air and space platform applications, are presented in this paper. Extinction measurements are essential to support the engineering development and the operational employment of a variety of aerospace electro-optical sensor systems, allowing calculation of the range performance attainable with such systems in current and likely future applications. Such applications include ranging, weaponry, Earth remote sensing and possible planetary exploration missions performed by satellites and unmanned flight vehicles. Unlike traditional LIDAR methods, the proposed techniques are based on measurements of the laser energy (intensity and spatial distribution) incident on target surfaces of known geometric and reflective characteristics, by means of infrared detectors and/or infrared cameras calibrated for radiance. Various laser sources can be employed with wavelengths from the visible to the far infrared portions of the spectrum, allowing for data correlation and extended sensitivity. Errors affecting measurements performed using the proposed methods are discussed in the paper and algorithms are proposed that allow a direct determination of the atmospheric transmittance and spatial characteristics of the laser spot. These algorithms take into account a variety of linear and non-linear propagation effects. Finally, results are presented relative to some experimental activities performed to validate the proposed techniques. Particularly, data are presented relative to both ground and flight trials performed with laser systems operating in the near infrared (NIR) at λ= 1064 nm and λ= 1550 nm. This includes ground tests performed with 10 Hz and 20 KHz PRF NIR laser systems in a large variety of atmospheric conditions, and flight trials performed with a 10 Hz airborne NIR laser system installed on a TORNADO aircraft, flying up to altitudes of 22,000 ft.

In this paper, we propose an optimization algorithm based on the intelligent behavior of stem cell swarms in reproduction and self-organization. Optimization algorithms, such as the Genetic Algorithm (GA), Particle Swarm Optimization (PSO) algorithm, Ant Colony Optimization (ACO) algorithm and Artificial Bee Colony (ABC) algorithm, can give solutions to linear and non-linear problems near to the optimum for many applications; however, in some case, they can suffer from becoming trapped in local optima. The Stem Cells Algorithm (SCA) is an optimization algorithm inspired by the natural behavior of stem cells in evolving themselves into new and improved cells. The SCA avoids the local optima problem successfully. In this paper, we have made small changes in the implementation of this algorithm to obtain improved performance over previous versions. Using a series of benchmark functions, we assess the performance of the proposed algorithm and compare it with that of the other aforementioned optimization algorithms. The obtained results prove the superiority of the Modified Stem Cells Algorithm (MSCA).

Miniaturization has always been a crucial challenge in the field of antenna engineering. In the recent past a number of researchers have shown that fractal geometry have potential to design smaller, broad band and multi band antennas. In this proposed work performances of log periodic fractal antennas of different flare angles have been investigated. Simulation results show that fractal log periodic antenna gives better performance in terms of gain, return loss and directivity. Performance of log periodic fractal antenna has also been investigated for flare angles 30°, 45°, 60°, 70° and 80°. In this proposed work fractal antenna gives best performance with 60° flare angle.

This paper presents a threshold decision circuit with an adjustable detection window designed in a 90-nm IBM CMOS technology. Together with an RF mixer, the decision Section realizes the circuit implementation of the back-end of a transmitted reference ultra wideband receiver, which is yet to be reported in literature. The proposed circuit is built on a differential amplifier core and avoids the use of integrator and sampling blocks, which reduces the device burden necessary for the architecture. Moreover, the detection window threshold of the design can be regulated by three independent factors defined by the circuit elements. The circuit is tested at an input data rate of 0.1∼2.0 Gbps and the core decision section consumes 9.14 mW from a 1.2-V bias supply (with a maximum capacity/Pdc ratio of 218.8 GHz/W). When compared against other reported decision blocks, the proposed detection circuit shows improved performance in terms of capacity and power requirement.

This paper presents an application of fuzzy approach to vehicle crash modeling. A typical vehicle to pole collision is described and kinematics of a car involved in this type of crash event is thoroughly characterized. The basics of fuzzy set theory and modeling principles based on fuzzy logic approach are presented. In particular, exceptional attention is paid to explain the methodology of creation of a fuzzy model of a vehicle collision. Furthermore, the simulation results are presented and compared to the original vehicle’s kinematics. It is concluded which factors have influence on the accuracy of the fuzzy model’s output and how they can be adjusted to improve the model’s fidelity.

Advanced composite materials are widely used as marine current turbines due to their high strength-to-weight ratios and excellent resistance to corrosion. A novel manufacturing approach similar to filament winding has been developed and is able to produce the Composite Material Marine Current Turbines (CMMCTs) that have significant advantages over traditional designs. This paper presents numerical results investigating the performance of ducted CMMCTs. The numerical approach was performed using CFD in a free stream of water with various hydrodynamic flow conditions. The investigation results provide an insight into the hydrodynamic design and operation of CMMCTs.

The present paper treats the agitation of shear thinning fluids in a cylindrical unbaffled vessel with a flat-bottom. Two kinds of impellers have been used: simple and double helical ribbons. This work is achieved with the help of CFD package (CFX-12.0), which is based on the finite volume method to solve the continuity and momentum equations. The effect of impeller rotational speed, fluid rheology, impeller size, impeller clearance from the tank bottom on the flow fields and power consumption have been investigated. Finally, a comparison between the two impellers is made. It was found that the best performance is obtained with double helical ribbon impeller placed at the middle of the tank, with moderate blade size and operating at Re g > 20. Our results have been compared with those of other literatures and a satisfactory agreement is observed.

Many problems of physical sciences and engineering are modelled by singular boundary value problems. In this paper, the variational iteration method (VIM) is used to study the time-dependent singular Emden-Fowler equations. This method overcomes the difficulties of singularity behavior. The VIM reveals quite a number of features over numerical methods that make it helpful for singular and nonsingular equations. The work is supported by analyzing few examples where the convergence of the results is observed.

The purpose of this paper is to apply an amended variational scheme, based on an adapted domain decomposition, for the solution of a second-order nonlinear boundary value problem that arises in applications involving the diffusion of heat generated by positive temperature dependent sources. The underlying idea of this approach is to decompose the original interval prior to the implementation of the iterative variational approach in order to improve the accuracy and acquire uniform convergence to the exact solution over the entire domain. Convergence analysis is given and then numerical experiments are carried out to make obvious the convergence, accuracy and efficient applicability of the method.

The level of safety of the transportation system in Akure, Nigeria was assessed by identifying the associated road safety problems and developing the corresponding safety performance indicators. These indicators were analysed with respect to accidents that occurred within the city from the year 2005 to 2009 based on the corresponding attributable risk measures. The results of the analysis showed the state of existing safety programs in Akure town. Six safety performance indicators were identified namely alcohol and drug use, excessive speeds, protection system (use of seat belts and helmets), use of day time running lights, state of vehicles (passive safety) and road condition. These indicators were used to determine the percentage of injury accidents as follows: 83.33% and 86.36% for years 2005 and 2006 respectively, 81.46% for year 2007 while years 2008 and 2009 had 82.86% and 78.12% injury accidents respectively.

One of the most challenging modelling problems in science is that of a particle crossing a gaseous mean. In sprinkler irrigation this applies to a water droplet travelling from the nozzle to the ground. The challenge mainly refers to the intense difficulty in writing and solving the system of governing equations for such complicate process, where many non-linearities occur when describing the relations and dependences among one influential parameter and another. The problem becomes even more complicate when not just a single droplet alone is assessed but a multi-droplet system is accounted for as, in addition to the inter-parameter dependencies, it is also observed an inter-droplet reciprocal affection, mainly due to electrical interactions between the hydrogen and the oxygen atoms of the different water molecules. An alternative to traditional classic approaches to analyse water droplet dynamics in sprinkler irrigation have been recently proposed in the form of a quantum approach, but the whole classic-quantum and single-droplet versus multi-droplet alternatives need to be discussed and pinpointed and these are among the main aims of the present paper which focuses on the theoretical part of the issue, thus highlighting the new perspectives of a deeper comprehension in the spray flow related phenomena.

Water pollution by toxic organic compounds is a problem and demand for efficient adsorbents for the removal of toxic compounds is increasing. In the present work, we studied the functionalization of SBA-15 materials via the co-condensation between an alkoxysilane and an organoalkoxysilane in the presence of P123 as structuring agent. Several types of ligands were used: 3-mercaptopropylmethyldimethoxysilane, N-[3-(trimethoxysilyl) propyl] aniline; aminopropyltrimethoxysilane; [aminoethylamino]-propyltrimethoxysilanes and [(2-aminoethylamino) ethylamino] propyltrimethoxysilanes. These materials exhibit BET surface area of 275–776 m2/g and total pore volume of 0.29–1 cm3/g, depending on the ligand types and contents. Elementary analysis results confirm the incorporation of both thiol and amine group in the materials. Batch adsorption studies shows that the adsorption capacity of phenol drifts on the amine and thiol functionalized SBA-15 is greater than that on pure SBA-15. A linear relationship was observed between the adsorption capacity and N/SiO2 ratio. It was shown that the presence of amine promotes interactions with water molecules, on the other hand, these results can also be explained by the basic behavior of N-functionalized materials.

Box-Behnken design was employed for the decolourization of synthetic dye bath effluent using solar induced photo catalytic degradation with mixed semi conductor catalysts. Four independent variables namely concentration of dye effluent, catalyst loading, pH and irradiation time was chosen as process variables. The optimum concentrations of dye effluent, catalyst dosage, pH, and irradiation time were found to be 60 mg L−1, 200 mg L−1, 7 and 100 min, respectively, for maximum decolourization of dye effluent (91.24%). Predicted values were found to be in good agreement with experimental values and as a result reflected the precision and the applicability of Response Surface Methodology (RSM) (R2=0.9785 and Adj R2= 0.9569).

Fusion bonded epoxy coating is one of the methods used to protect steel against corrosion. The primary objective of this research reported in this paper is to evaluate the bond strength of epoxy coated bar splices confined with lateral reinforcement. Six full scale beams specimens, designed to fail in bond- splitting mode, were tested in positive bending. Each beam was reinforced with bars spliced in the constant moment region at mid span. The main variables were the amount of transverse reinforcement in the splice region and the coating to the bar. Test results indicate that transverse reinforcement improves the bond strength of coated bars and the ductility of the beams. The bond strength of coated bars is 93%, 72% and 59% of uncoated bars for confinement indices of 1.8, 1.4 and 1.26 respectively. Moreover, a bond reduction factor of 1.35 is suggested for use in code in place of 1.5,when the confinement index is greater than 1.4.