مجله علوم و فناوری های پدافند نوین
سال سوم شماره 2 (پیاپی 8، تابستان 1391)

Due to the main role of XOR-XNOR gates as the building blocks of many basic arithmetic circuits such as multiplexers، full adders، compressors etc، new methods of improving the speed and power consumption performance has been reported. As the dimensions have been reduced to deep submicron scale، noise immunity has also become an important parameter along with speed، power consumption and size. Herein، the functional properties of a number of these XORXNOR gates are compared and a new low power XOR-XNOR gates with improved noise immunity XOR-XNOR gates using 10 transistors is proposed. In passive defense issues، the immunity to electromagnetic disturbances is of paramount importance. Therefore increasing the circuits’ immunity to noise will help the circuits’ function properly against electromagnetic disturbances. The simulation results with 0. 18 (μm) technology in an Hspice software for all supply ranges from 0. 6 (V) to 3. 3 (V) has shown that the new proposed circuit has lower power consumption، an improved PDP with better noise immunity compared to the previous reported circuits.

One of the most important factors in determining the necessity of passive defense consideration in civil project is the amount of probability of military attacks for that project. Therefore، in the risk analysis of passive defense studies، it is very important to determine between two or more civil projects which one have more probability to be attacked by military. This probability can be equal to the parameter that is known in different risk analysis methods as the probability of occurrence (O). This parameter is calculated typically quantitatively or qualitatively by making predictable criteria and by weighting them in different projects. But regardless of what analysis method has been used in determining the probability and that analysis method is based on how many of criteria، always some of the criteria remain as unpredictable issues. This paper offers a new method، based on fuzzy logic that have directly related to level of knowledge of attacker’s force (X) and can be used for calculation of probability increase of occurrence due to unpredictable criteria () in the different projects. By adding it to the value of probability of occurrence due to predictable criteria (O)، the amount of modified occurrence probability () can be calculated in the range that unpredictable criteria has great importance (very low probability range).

Low-Power Linear Regulators are important in medical، communication and military application such as bullets of gun with input supply، Maine network of marine، low-consumption satellite circuits and implantable systems in the alive creature’s body. In this paper، a full integrated linear regulator based on the FCOC technique is proposed. The regulator using three blocks A،B،C and five blocks A،B،C،D،E in the TSMC-0. 13µm CMOS technology have been developped. Proposed regulator has been simulated by star-Hspice. Output voltage ripple of three-block design is 3. 5mV، while the output current is 20µA at the frequency of 2Hz. Similarly، of five-block design ripple is 1mV. This regulator has good performance in high frequency. Output voltage ripple in three-block and five-block designs is less than 14mV and 3. 2 mV respectively at the frequency of 1-100MHz.

In this research، the planer and variable polarizing undulators are investigated and compared. Regarding field equations in to the undulators، independent relativistic electron approximation and Lorentz''s force، the trajectories of electrons in undulators are calculated. Using calculated electrons'' acceleration، theory of accelerated charged particle radiation and Lienard-Wiechert equation، the power of free electron laser are investigated. Complexity of the obtained equations and their analytical difficulty caused numerical investigation of the results. The results are represented by two and three dimensional diagrams. The comparison of output power from free electron laser with variable polarizing undulator and with planer undulator show that output power of helical undulators are more than linear undulators. For helical undulators with zero phase difference، the maximum output power is at the points where summation of square of undulator parameters is equal to a constant. The role of the phase difference in the helical undulator has been investigated. The results showed that with π/4 and π/2 phase differences، output power of free electron laser at equal undulator parameters are maximum. Comparison of these two state showed that output power with phase difference of (π) /2 is more than π/4. The harmonics of planer and variable polarizing system are evaluated and compared.

Using air attacks on cities have been known as a common strategy in the recent wars. Hence، it is necessary to assess the vulnerability of cities to air attacks and provide appropriate solutions to mitigate damages. This goal is achieved by using passive defense considerations and urban planning methods. In this study، district 1 of region 11 of Tehran municipality has been used as the study area. This zone is introduced in Tehran’s outreach plans as an important part of the city، because of establishing strategic land uses، and hence evaluating its vulnerability is important. In this research، the vulnerability assessment of the region of interest to air attacks is accomplished using the analytical hierarchy process (AHP) method and the geographic information systems (GIS). The findings of this assessment show that 92. 4% of construction blocks in the region of interest are included in the range of medium to high vulnerability.

Localization systems are usually used for detecting moving and offensive targets of enemy. The sound localization، however، is one of the main approaches in passive defense which has an impending role to aggression of enemy. This kind of localization method is carried out in a passive way، without emission of any signals and cannot be detected easily. The acoustic signals emitted by a sound source are used to detect its position. Sound source localization is estimated by measuring the time difference of sound from the microphone array. Due to the distance between the microphones in an array، sound reaches the microphone with shifting times. There are many various methods for estimating this time difference of the sound. The locus of sound source position creates a series of hyperbolic; and the source location is obtained by solving a set of nonlinear equations of these hyperbolic. Sound positioning algorithms generally solve these equations by linearization and geometric symmetry. In this study، instead of nonlinear hyperbolic equations، the trigonometric relations of geometric symmetry in a four microphone array are used to obtain the position of sound source. The results show that the trigonometric method is more accurate and less sensitive to noise as well as lower computation load، compared to the sophisticated hyperbolic equations. The mean error induced by noise is about 8. 9% and 13. 1% in the trigonometric and hyperbolic method respectively.

Nowadays graphs are widely used in many domains such as software، network، web، chemistry، biology and even communication and sociology to modelling and data processing. In many applications، graphs are very large and complex. So understanding the structure and extracting useful information from them is become more challenging. Here، graph summarization algorithms could be a suitable solution. In this paper، a new graph summarization algorithm has been proposed which is able to produce different summaries from different points of view from one graph regarding to user’s interested subjects. Also users can control the resolution of produced summaries. Moreover، the algorithm is developed using Neo4j database which is one of NoSQL databases. Also، the algorithm using different laboratorial and real data sets is tested. The results show that the produced summaries are in high quality position and also the efficiency and scalability of the algorithm is better that the similar one.

In this paper، prediction of maximum response of a structure subjected to the impulsive loads، using of simple analytic relations developed for linear SDOF systems is presented. Duration of underwater explosion pulse in comparison with the natural period of studied structure in this paper is enough short to consider it as an impulsive load and hence، maximum response of the structure can be estimated without dynamic analysis. After modeling of concrete wall of cylindrical water tank used as an ''explosion test chamber'' in SAP2000 and explosion loading and analyzing of it in both static and dynamic methods، Results obtained from both SDOF and MDOF methods compared with each other and hence، the accuracy of the analytical relations based on the SDOF method in the estimation of maximum dynamic response of the structure was investigated. Considering that the response of the structure is mainly function of the impulse of the explosion in the structural and loading conditions studied in this paper، using an explosion loading function evaluating the impulse more precisely such as linear triangular pulse extracted from the field tests data results in more accurate response of a structure.

In this paper، Zeolite NaY was synthesized by sol-gel method in the absent the presence of organic templates and additives. Then، using ion-exchange method، it was transformed to zeolite AgY. In next step، a manganese dioxide nanoparticle was synthesized in the pores of zeolite AgY by confined space (CS) method. Nano-MnO2/Zeolite AgY composite was characterized by SEM، XRD، IR and AAS techniques. The decontamination reaction of 2-chloroethyl phenyl sulfide (mustard agent simulant) and dimethyl methylphosphonate has been investigated by nano-MnO2/Zeolite AgY composite. The results of GC analysis showed that 2-CEPS is produced about 86% by composite after 24 hours and it is changed to less toxic chemical products. The major of which، identified by GC-MS instrument، was phenyl vinyl sulfide (PVS). On the other hand، 31PNMR analysis showed absorption of DMMP of about 87% after 30 hours.