Investigation of X Frequency Microwave Absorbance of Ferrite Nano-Composite in Polyurethane Matrix
بزرگمهر
مداح
دانشگاه جامع امام حسین(ع)
author
علی
داوودی
علوم تحقیقات، واحد خراسان رضوی
author
محمد رضا
خاکباز
دانشگاه جامع امام حسین(ع)
author
text
article
2016
per
In modern battlefield, Radar has emerged as an important sensor to detect and target the military equipment of enemy. The camouflage against radar sensor is mainly achieved through the use of radar absorbing materials (RAM). These materials absorb most of the radar incident energy, thereby reducing the reflected signal to minima, and thus locking the capability of radar detection. In this study, the ability of different nanocomposites were examined to measure the reflection loss. Polyaniline, iron oxide and titanium oxide nanocomposite on Polyurethane substrate was successfully tested and absorbed good amount of radar waves. In order to optimize the reflected loss (the amount of absorbance), the effect of parameters such as thickness and concentration of nanocomposite were considered. The results indicated that the maximum loss in range of 8-12 GHz for a thickness of nanocomposite as 7.5 mm, is about 22.5 dB at 9.7 GHz .
Journal of Advanced Defense Science & Technology
Imam Hussein University
2676-2935
7
v.
1
no.
2016
1
8
https://adst.ihu.ac.ir/article_204170_05c15ba5cb9ed6e26550087b68ffd2de.pdf
Modeling of Required Time to Reach the Maximum Phosgene Oxime Pollution in Runoff (Case Study: The Adjacent Areas of Kan River and North Flood Return of West Tehran)
صفا
خزائی
دانشگاه جامع امام حسین (ع)
author
محمد جواد
کاظمی
دانشگاه شهید بهشتی
author
text
article
2016
per
Water pollution caused by chemical materials in different forms such as chemical bombs, terrorist attacks, and reluctant events is one of the main concerns of human societies. Chemical pollutions can permeate into surface waters because of the release of pollutions on the ground or rainfall in the time of air pollution. The main objective of this study is to model the surface water pollution reaching its maximum level after entering the chemical pollution. In this study, diffusion of chemical pollution caused by phosgene oxime (blister agent) in all areas alongside to Kan River and the reverse flood area of the west of Tehran is modeled using ArcGIS and SWMM softwares. Based on the results, the maximum density of pollution depends on the return period of rainfall, the pollution density, and type and slope of the ground. Also, the time to reach the maximum pollution is almost constant between 3 to 4 hours.
Journal of Advanced Defense Science & Technology
Imam Hussein University
2676-2935
7
v.
1
no.
2016
9
18
https://adst.ihu.ac.ir/article_204171_f27be658bbc1b263a00716a978b0309d.pdf
Optimal Mix of Distributed Generation Allocation to Improve the Security of Energy Supply in Defensive Sites Using Principles of Passive Defence
reza
ghaffarpour
دانشگاه امام حسین(ع)
author
alireza
jam
دانشگاه صنعتی امیرکبیر
author
alimohammad
ranjbar
دانشاه صنعتی شریف
author
text
article
2016
per
Security of electrical energy supply in defencive sites is affected by different parameters like natural disasters and enemy attacks. So, attention to principles of passive defence for design and enhancement of electrical networks in defencive sites is critical. The objective of this study is to increase security of energy supply in defencive sites from the standpoint of passive defence. Due to the presence of DG units and the uncertainty of their power, common methods of security evaluation of energy supply are not applicable directly. For this propose, a new framework for optimal allocation of hybrid energy resources in these sites is presented so that networks technical constraints is satisfied beside energy resources uncertainty and sensitive loads priorities. Supply adequacy of consumers is evaluated by solving a set of optimal power flow equations. Finally, a comprehensive algorithm based on imperialist competitive algorithm, scenario reduction, and optimal power flow is proposed. The optimization problem is formulated as combination of a mixed integer nonlinear programming main problem and a set of nonlinear programming sub problems, taking into consideration the system constraints during all computational steps. The proposed model is presented in MATLAB and GAMS environments and optimal mix of energy resources is obtained to increase energy security of defensive sites and to reduce outage of critical loads, towards principles of passive defense (proliferation, diversification, and dispersation). Final results show the effectiveness of the proposed algorithm in optimal design of hybrid energy resources and remarkable improvement of energy supply security.
Journal of Advanced Defense Science & Technology
Imam Hussein University
2676-2935
7
v.
1
no.
2016
19
32
https://adst.ihu.ac.ir/article_204172_ad591dc3a35725b0f65048269763a544.pdf
Analysis of Normal Impact on Sandwich Panel with Considering Difference Energy Absorption Mechanisms
seyed sajad
jafari
دانشگاه آزاد اسلامی همدان
author
saeid
feli
دانشگاه رازی
author
milad
ranjbaran
دانشگاه تهران
author
text
article
2016
per
In this paper, a new analytical model has been presented for energy absorption calculation of aluminum-foam sandwich panels under high velocity impact. The panels consist of foam core sandwiched between two aluminum skins. In analytical model, cylindrical rigid projectile with flat ended has been considered. In the quasi-static loading, by using the springs-mass model, energy absorption of aluminum skins with considering difference energy absorption mechanisms has been calculated. Also foam absorbed a partial of projectile energy by crushing. Energy absorption of aluminum-foam sandwich panel was calculated and energy balancing equation has been employed for determination the ballistic limit and residual velocity of projectiles. The results of ballistic limit and residual velocity computed by new model presented good agreement with experimental and numerical results. Also the effects of foam density, projectile mass and diameter in energy absorption of sandwich panel has been investigated.
Journal of Advanced Defense Science & Technology
Imam Hussein University
2676-2935
7
v.
1
no.
2016
33
43
https://adst.ihu.ac.ir/article_204173_55ea3939959afc5ca01c1393c2405544.pdf
Vulnerability Analysis Concrete Tanks Liquid Storage under Air Blast
علیرضا
سروقد مقدم
رفتار سازه ها در برابر انفجار
author
A. R.
Sarvghadmoghadam
International Institute of Earthquake Engineering and Seismology
author
M.
Ziaei
K. N. Toosi University of Technology
author
text
article
2016
per
According to the strategic geographic position of IRAN with the probability of terrorist threats and air strikes, and also the important crucial role of the tanks, their construction by taking passive defense measures and considerations is necessary. Because of few researches on the vulnerability of tanks against the loads due to explosion, investigate the importance of this type of structures against blast loads is increasing. In present study a hypaethral cylindrical concrete tank, exposed to air blasting by one cubic explosive TNT with weight of 352.08 kg has been modeled. The tank is modeled in four situations such as: empty state, , and of body height full of liquid. The results of simulation showed that damages of compressive and tensile in the empty tank are more critical than other modes, and the manner of hypaethral concrete tanks against explosive loads is different from their manner against seismic loads caused by the earthquake. It was also shown that the conwep method has considerate only the effects of the explosion and at least 25% reduction achieved in compressive damage compared with the results of the AUTODYN. The results of this study can be used in retrofitting and safe design of fluids storage tanks to resistance against the blast loads.
Journal of Advanced Defense Science & Technology
Imam Hussein University
2676-2935
7
v.
1
no.
2016
45
58
https://adst.ihu.ac.ir/article_204174_f01019e95457b7de13ba9417c9d32ed3.pdf
Simulation of Kerr Lens Behavior in a Ti:Sapphire Oscillator with Symmetric and Asymmetric Resenator
Abdollah
Malakzadeh
سپاه
author
Seyed Reza
Zare Kalate
سپاه
author
Mohammad Javad
Kamjoo
سپاه
author
text
article
2016
per
Femtosecond pulse lasers are one of the most widely used lasers. Femtosecond oscillator is first step to generate powerful femtosecond pulses. In this work, the laser beam propagation in an oscillator in symmetric and asymmetric designs without Kerr lens effect inside a Ti:Sa medium was simulated and the cavity stable operation conditions have been obtained. Then, Kerr lens modelocking behavior is simulated and the situation compensating the beam astigmatism is achieved. Split-step method has been used to obtain the beam intensity change in the Ti:Sa rod and shooting method has been utilized to calculate the beam spot size on the first cavity mirror. Assuming no Kerr lens effect, influence of the cavity length changes in laser beam characteristics is investigated and considering the Kerr lens effect in the laser rod, influence of the rod position in the beam characteristics and beam propagation is simulated. Finally, by considering the simulations results, conditions to achieve soft or hard aperture modelocking are discussed.
Journal of Advanced Defense Science & Technology
Imam Hussein University
2676-2935
7
v.
1
no.
2016
59
70
https://adst.ihu.ac.ir/article_204175_5fb1d99a0f93b751b5d8bbc12bd2dc1e.pdf
An Optimal and Transparent Framework for Automatic Analysis of Malware
Saeed
Parsa
دانشگاه علم و صنعت
author
Amir
Gooran Oorimi
دانشگاه علم و صنعت
author
text
article
2016
per
Malware is the most important security threat in cyberspace. Some statistics show that over 315,000 malware are released, every day. Certainly, it is not possible to analyze all of these malware, manually. That's why the security vendors are obliged to use software capable of analyzing suspicious executable files. These software determine behavior of suspicious files automatically. Several tools such as Anubis and Cuckoo are produced in this area. The problem of these tools is lack of transparency. Some malware use this sort of weaknesses to recon analysis environments. To resolve this problem some solutions using hardware-assisted virtualization is presented. However, these solutions impose a great run time overhead on the program execution. In this paper an automated malware analysis framework is presented that is both transparent and optimal. This framework in addition to being resistant to malware with split personality features, may also be used to analyze the large amount of malware released every day without adding extra hardware resources. This framework uses dynamic analysis approaches with hardware assisted virtualization technology to analyze suspicious code. The dynamic analysis approaches used in this framework include sandboxing and system calls sequence analysis. Analysis based on hardware-assisted virtualization technology is applied to provide transparent analysis environment.
Journal of Advanced Defense Science & Technology
Imam Hussein University
2676-2935
7
v.
1
no.
2016
71
80
https://adst.ihu.ac.ir/article_204176_c68e2476ad2d6ee8f1cd1aff53182fe3.pdf
An MCMC-baesd Particle Filter for Multitarget Tracking within Raw Measurements
M.
R. Danaee
پردازش
author
text
article
2016
per
This paper examines multitarget tracking within raw measurements which has always been considered to be a hassle. This was achieved by separating the state space model of each target into linear and nonlinear subspaces. Then, the Rao–Blackwellization principle was utilized to derive the optimum importance density for special kind of sensor which generates both split and merged measurements within a pixelized observation area. To relieve the complexity associated with the achieved optimum importance, the Gibbs sampler, the well-known sampler from MCMC family, is used to sample from the optimal importance density. The synthetic multitarget tracking scenario using raw data will then be used to show that our new Gibbs sampling method could reach a compromise between accuracy of tracking and computational expense. The proposed idea is motivating to be used in applications where sampling from the optimum proposal density is practically impossible.
Journal of Advanced Defense Science & Technology
Imam Hussein University
2676-2935
7
v.
1
no.
2016
81
94
https://adst.ihu.ac.ir/article_204177_f766a1838f1b97ce4ad72fd4b485c53a.pdf