Advanced Defense Science and Technology
Year:2013 | Volume:4 | Issue:2 (12)|Papers Count:8

Wireless Ad Hoc networks are among different wireless networks which are extensively studied in the past few years. Ad Hoc networks consist of several mobile nodes with alternate locations. Hence, such a network, has to employ resilient routing algorithms to manage node movement and correct routing in the presence of broken links and outage of availability seamless to users of any two communicating nodes. In this paper different routing strategies based on neural network techniques are studied. Then a new algorithm based in shortest path method and Hopfield neural network is proposed. The proposed algorithm is then simulated using NS-2 network simulator. Numerical results show that the new algorithms can outperform traditional DSR and AODV and has shorter traffic overhead.

Botulism is a dangerous neuroparalytic syndrome caused by Clostridium botulinum neurotoxins (serotypes A-G). The more studies have shown that the binding domains in all neurotoxin types (A-G) have a great importance in immunity against the botulism syndrome and nowadays, this domain has been introduced as a vaccine candidate. In this study, for evaluation of adjuvant effect of Gold Nanoparticles (GNPs) on a vaccine candidate, the botulinum neurotoxin type E binding domain was used. In vaccine studies one of the problems is the presence of a potent and biocompatible adjuvant with fewer side effects. For developing of new adjuvants, the adjuvant properties of GNPs to Freund's adjuvant (FA) was compared. A recombinant binding domain BoNT/E conjugated with GNPs was prepared and injected four times. The animals were enrolled in two groups, one of which was injected with FA and the other one with GNP-Ag. Then, the antibody titers were compared with each other. Ultimately, the mice were challenged using active BoNT/E. The results showed that the immunized mice with GNP-Ag and Ag-FA produced high titers of antibody and presented immune response comparable with together. Regarding antibody induction, challenging results and the GNPs biocompatibility, this kind of nanoparticles might be introduced as a candidate new adjuvant in the future studies.

Considering passive defense in construction and rehabilitation of military and residential structures is a proper method for blast-induced damage mitigation. In this paper, the behavior of end plate bolted connections under blast is studied. To assure the accuracy of finite element models, verification is carried out using the results of an experimental test. Nonlinear dynamic analysis is carried out considering high strain rate effects. A 5-story structure is designed according to the national steel structures code using ETABS and one of the first storey connections is studied under blast load using nonlinear dynamic analysis in ABAQUS considering the effects of high strain rates. The results show that the beam experiences significant torsion. Moreover, the critical area in moment connection is the area adjacent to lower bolt holes as well as the area between end plate and lower beam flange. It is also observed that the use of small bolts in higher number provides more desirable response in blast loading.

Nowadays, camouflaging the warfare equipments particularly aircraft, helicopters and drones are inevitable. Camouflaging in the radar range means attenuation, reflection and dispersion of radar waves. This operation can be achieved by different methods most notably, by reducing the radar cross section or using radar absorbent material. In this study different nanocomposites were tested for loss of radar waves. As a result of this research poly-aniline nanocomposite of iron oxide (III) nanoparticles and titanium nanoparticles were the most effective. Also a few experiments were carried-out on the thickness and percentage of nanocomposite constituent. This work was carried out in three stages. In the first stage, Fe3O4 nanoparticles were prepared by co-precipitation method using NH3 solution. The crystal structures and morphology of nanoparticles were investigated and characterized by X–ray diffraction (XRD) and scanning electron microscopy (SEM). In the second part, conducting polyaniline/nanoparticles (TiO2 and Fe3O4) composites were synthesized by in situ polymerization method with ammonium persulfate (APS) as the oxidant and under an ice-water bath (0 °C). In last step, nanocomposite powders was completely dispersed in paraffin and was followed by casting process on test plate. The radar absorbing property of nanocomposite was investigated by vector network analyzer at the frequency range of 8-12 GHz. The best absorption was caused by the nanocomposite with concentration of about 10% and thickness of 4 mm. Maximum reflections recorded was about 33.3 dB at 9.5GHz.

Nowadays, with the increase of terrorist attacks near the urban areas, the building design under the blast loadings is really significant, especially for some important buildings and vital arteries. When an explosion occurs, the blast waves can cause severe damages to the structures and endanger the lives of people. Since the existing steel structures are usually designed to the common gravity and seismic loads, it is necessary to investigate their performances under blast loadings. In this study, analytical studies have been done for 3D structural models of special moment frames (SMF), concentrically braced frames (CBF) and eccentrically braced frames (EBF) with different number of stories 3, 5 and 10. The nonlinear dynamic method is applied for analyzing the models under two different levels of blast loadings. The blast load pattern and other criteria are based on the UFC 3-340-02. The plastic hinge rotation, ductility ratio, performance levels, brace axial forces, shear forces and flexural moments in all models are obtained from the analysis and compared with each others. Based on results, It can be said that the EBF systems generally show the better performances than other systems under blast loadings.

Exponential growth of information in the cyberspace alongside rapid advancements in its related technologies has created a new mode of competition between societies to gain information dominance in this critical and invaluable space. It has thus become quite critical to all stakeholders to play a leading and dominant role in generation of information and monitoring of voluminous information uploaded to this space. The dominant role of a stakeholder in cyberspace provides him with new opportunities and builds up his capacity for passive defense in the political, ethical, scientific, educational and recreational fields. However, to gain dominance in the monitoring of vast amount of information in cyberspace requires new techniques and approaches for online monitoring quite different from traditional ones. Concerned with the latter case, we limit our focus in this paper on blogs as an important part of the cyberspace social media and present a new technique for online detection of changes in blogs. We show that our technique works favorably compared to techniques that require cooperation and synchronization between information providers. This is achieved by providing a new architecture and restricting the search for changes in high volumes of blogs only to changes in the RSS (Rich Site Summary) of each blog.

Polarimetric Interferometric Synthetic Aperture Radar (PolInSAR) is a Radar polarimetric technique that provides the ability to use the information of different polarization channels to investigate the structure and perpendicular layers of scatters. Estimating the height of trees is one of the significant applications of PolInSAR which has high importance in the forestry and passive defense fields. One of the major problems to estimate the tree height using PolInSAR is evaluating the impact of environmental factors such as humidity, slope, surface roughness and species. The goal of this study is to conduct several experiments for investigating the impact of such environmental factors on tree height estimation. In this study, the height of trees is estimated in different scenarios using the well-known Random Volume above Ground (RVOG) model. Based on the results obtained in this study, the roughness and humidity parameters have, respectively, the maximum and minimum impact on the accuracy of estimating the height of trees.