Advanced Defense Science and Technology
Year:2012 | Volume:2 | Issue:4 (6)|Papers Count:11

Multistatic radar systems have many applications such as homeland security, anti-air defense, anti-missile defense, and ground target detection. In this article, a multistatic radar system, capable of detecting a flying object within the coverage area and computing its position and velocity in a three-dimensional coordinate system, is simulated.Calculating the radar cross section, the kind of the object is recognized. If the object's path follows a specific equation of motion, the path can be estimated only after the first detection. Otherwise, the simulation procedure estimates the object's path by tracking it. Simulation results show that the proposed method can effectively be applied to applications such as anti-air defence systems. To increase the signal to noise ratio and vastness of the coverage area around a specific point, a solution to optimally locate the radar sites, is presented. As the design parameters are conflicting, this is achieved using a multi objective design technique.

Directional simulation, among techniques for reliability analysis of engineering structures, is well known. In this context, directional simulation in load space, because of the advantages of lower dimension of working space, is of considerable interest. As expected due to structural resistance variability, the location of the relevant limit state (s) along any simulated direction, is no longer constant and must be taken as a random variable. The accuracy of the results obtained using this type of simulation therefore depends on how well this random variable probabilistically is modeled in analysis. In order to describe probabilistic properties of this random variable, one simplified solusion is to use only the first two moments which implies the use of normal distribution. This paper intends first to verify how taking this distribution may affect the accuracy of the results (i.e. estimation of the probability of failure) and second, to propose alternative solution (s) in order to enhance the quality of the method in the cases where the above simplified method may lead to poor results. In the examples given in this paper, the quality and workability of the proposed solution (s) are compared with the simplified solution and finally some practical recommendations are given.

Nowadays, because of recent achievements in wireless technology and the need for pervasive usage of services, wireless networks usage have been soared widely. In addition, Adhoc wireless networks are popular because of not requiring central controller, adaptation to movements, and its high customizability. The important aspects of this network are routing algorithm and establishing connection between source and destination. In this paper, we propose a proactive routing algorithm for wireless adhoc networks based on swarm intelligence and reinforcement learning.The proposed algorithm, decreases the packet delays in network, lowers the costs of receiving packets, and improves performance of network as a whole. Functionality of this algorithm has been tested with NS simulator and the results have been compared with DSR and AODV algorithms.

Nanoparticels of MgO were synthesized by Aero gel method and their size and shape were determined by X-ray diffraction and Scanning Electron Microscopy. MgO nanoparticles were mixed with DMF/THF (2: 3) solution of polystyrene and after optimization of electro spinning parameters, subjected to electro spinning to produce Nano composite fibers.Morphology of fibers was studied by scanning electron microscope. Decontamination of mustard agent-simulant (2-chloro ethyl ethyl sulfide) was performed in thepresence of these fibers. The adsorption of 2-CEES was studied using GC. The amount of adsorption on the nanofibers prior to the addition of nanonoparticles and nanoparticles alone were studied too and the results were compared.

Electromagnetic waves can have destructive effects on human health. In modern war strategies, electromagnetic methods are used to disable the manpower. Radiation of electromagnetic fields could change some physiological parameters of the body, such as blood glucose level. So it needs frequent blood glucose measurement by sampling. In this article, we have proposed a new non-invasive method for blood glucose measurement. This electromagnetic method can be used for measurement on the tissue of a living creature. In this method, a bobbin is used as a sensor and a solution that contains the glucose (i.e. blood) is poured in its core. Any change in glucose concentration causes the dielectric solution parameter variation and hence the impedance of the bobbin changes. The ratio of the secondary bobbin signal to the reference signal of the primary bobbin, T/R ratio, is measured in RF frequencies and is used as an index of circuit impedance variation. Normally, T/R would only change as a function of glucose, but there are other interference parameters such as the solution volume, which affect the measurements. In this paper, the measurement setup and the method of changing glucose concentration is proposed. It has been shown that the volume variation has higher effects on the measurement output compared to that of glucose. A method has been proposed for compensation of the volume changes and finally, it has been shown that after this compensation, there will be a good correlation between the glucose concentration and the T/R ratio.

In this paper, an efficient method for camouflage assessment in remote sensing images is presented. The proposed method consists of two main parts including template matching algorithm and UR-SIFT (Uniform Robust Scale Invariant Feature Transform) feature extraction algorithm. In the first part, the distinctiveness between target and background based on template matching algorithm is computed and using a Gaussian function a quantitative measure is presented for description of target camouflage. In the second part, the detectability rate of the target is investigated based on UR-SIFT algorithm which is an improved version of the well known SIFT algorithm. This algorithm has been developed for feature extraction in remote sensing images. If the target has not been extracted using UR-SIFT algorithm, it can be concluded which target are concealed in the its background. The proposed method has been tested using various satellites and aerial remotely sensed images in four-camouflage status and evaluated based on its performance. The results indicate the appropriate performance of the proposed method in camouflage assessment in remote sensing images compared to the Darg operator.

Since a secure voice or data session is very important in military HF communication, it needs a HF modem designed with cipher capability. Whereas multipath and Doppler affection are very adverse in HF sky-wave mode, so the production of a robust modem is essential for military application to compensate channel distortion. Then channel estimation block is very important and this paper proposes an enhanced method for channel estimation. The OFDM pilot based channel estimation with wiener filtering is a robust method that estimates channel excellently with minimum pilot density. The result show that proposed method can increase bit rate with decrement in pilot density, which allows use of a stronger channel coding and subsequently a lower bit error rate. Simulation shows that the bit-error rate of the proposed method passes the American military standards.

Hydroelectric power plants as a clean source of electrical energy can play a prominent role in the country's electricity supply. But, given the complexities associated with selecting a suitable place to build these structures, various factors must be considered. On the other hand, effective international diplomacy of Iran causes many threats against Iran. This highlights the requirement of passive defense argument in locating the critical facilities such as hydroelectric power plants. In this study using a GIS in the context of TOPSIS multi-criteria analysis, examination of factors to locate a hydroelectric power plant in Isfahan province has been accomplished.

The EGF family include13 members and the hEGF as founding member of this family involves in epidermal wound healing. Epidermal growth factor is an essential polypeptide for wound healing and promoting mitotic division. In this study, human epidermal growth factor gene was adapted from gene bank and its codons were optimized according to codon preference of E. coli BL21. The gene was prepared as synthetic construct in pET21a (+). Then the recombinant construct was transferred to E. coli and hEGF gene in the vector was expressed under the control of inducible T7 promoter. Purification was done using affinity chromatography. The bioassay results of three different doses showed that recombinant protein has significant effects on growth of NIH-3T3 cell line.