فصلنامه پدافند غیرعامل
پیاپی 4 (پاییز 1389)

In this computational research, a photonic crystal filter has been designed to protect passive defense sensors in α- band of IR radiation and its performance at 2.8 µm Hydrogen-Fluoride laser has been studied. The photonic crystal assumed to be a silicon elliptical bars at air background with trigonal geometry was designed. Optimum geometry for 2.5 µm wave was found and its filteration performance for considered laser wavelength was examined. Such a filter with considered large and small diameters show desired performance.

One of the issues that is now of high interest to civil engineers is the hardening of structures against unusual loads(including blast loads, fire-caused loads, impact loads). One of the features which has attracted attention in the field of structure hardening is the application of the capacity derived from chain performance to harden structures against failure caused by unusual loads. In this regard, since the armed concrete dalle is considered one of the main members of concrete structures, their behavior in the chain conditions and their ability during the chain performance greatly affect the lives of personnel and the general sustainability of concrete. In regard to this important point, their hardening is of utmost importance. Therefore in this research, firstly an armed concrete dalle similar to the test samples, has been modeled and analyzed using the ABAQUS software and then ensuring the ability of this software to model and analyze the relevant sample, all kinds of hardening and improving the behavior of concrete dalle using FRP in the chain conditions, has been reviewed. In this research, various status has been studied taking different models of fiber formation and various thickness into consideration. The results showed that the loading capacity of dalle and its formability increased by 50% and 30% respectively and the FRP- reinforced dalles have suitable performance in the chain conditions and can prevent failures caused by unusual loads.

In this paper, an attempt has been made to investigate the effects of the smoke containing Brass powders. Also the effects of smoke having a mixture of powder and fiber graphite on thermal wave are investigated. The results show that the camouflage coefficient of the Brass powder in infrared range is significantly larger than mixture of powder and fiber graphite. In addition, it is shown that powder particle size have a substantial effect on the camouflage coefficient.

Since in passive defense, one of the important aims is to decrease the effects caused by enemy attacks, one of issues whose safety must be taken into special consideration is nuclear reactors. In regard to passive defense, one of the main indicators is reactor safety. In third generation nuclear reactors, dimensions of core and also the kind of coolant and enrichment percentage of fuel have changed compared to the second generation that eventually, all of them have culminated in higher safety of these reactors than previous generation reactors. Therefore in this article the aim is based on a comparative investigation between two same power reactors of second and third generations, that the neutronic parameters of both reactors such as: K∞, Keff and its details and thermal-hydraulic parameters such as: power density, specific power, volumetric heat rate, released power per fuel volume unit, volume and mass of clad and fuel (consisting fissile and fertile fuels), be calculated and compared together. By this comparision, the efficiency, modification and also more safety of third generation nuclear reactors compared to the second generation which have same power, can be figured out.In order to calculate the cited parameters, some information such as: core dimensions, the pitch of lattice, the fuel matter, the percentage of enrichment and the kind of coolant are used. For calculating the neutronic parameters, a neutronic program entitled: SIXFAC and also related formulas have been used. In the meantime, to calculate the thermo hydraulic and other parameters, analytical method and related formulas have been applied.

With the inception of science and technology revolution, especially information, communications, electronic and computer technology in the recent years, the fourth generation wars have been designed and experienced in recent wars as well and continue their evolutionary routes. One of the most significant aims of information and communications-based wars is the financial and banking markets of countries which are waged to destroy and corrupt economic markets of these countries. Within the past three decades, a new definition of crime has appeared in the economic affairs which due to its highly destructive dimensions in the national and international levels have attracted the attention of economic, political, legal systems of countries and international organizations and this crime is nothing but money laundering. Money laundering or money cleansing is a criminal activity in a large scale, group, continuous and long term which can go beyond the political boundaries of a hypothetical country. Money laundering has harmful effects on economy, society and politics, corruption and instability of economy, weakening private sector and privatization plans, reduction of government control on economic policies, corruption of government systems, public mistrust, discredit of governments and state economic organizations, development of criminal business, government and medical care costs upheaval, reduction of government tax revenues, instability and lack of sustainability in the world market, damaging global efforts to establish free and competitive markets and disruption in the economic growth and so on, are only parts of these effects. In the recent years, the financial systems have taken advantage of a new form of performance called electronic model. Criminals misuse the economy and its globalization and advances derived from information and communications to conceal their illegitimate income. They use plenty of techniques including swift money transfer from one country to other countries or companies and corporate cooperation in order to clean inappropriate sources. On the other hand, due to its destructive nature, Mafia-like powers and governments attempt to take advantage of this method as a passive defense attack in order to disintegrate the economic systems of other countries and therefore their political systems. Therefore recognizing this new phenomenon and the appropriate legal and technical methods to prevent it is consistent with achieving the passive defense which is an undeniable necessity these days.

Rapid screening of seismic vulnerability is conducted for quick and cost-effective identification of existing buildings and the crisis management information of a city or area can be completed using its results and the application of GIS techniques. This paper introduces a new, comprehensive and efficient method in rapid seismic screening of buildings in a manner in which using the results of this method and case study of the desired area of the Metropolitan city of Isfahan, the vulnerability of its buildings have been estimated and with the application of GIS techniques, pre and post crisis measures can be taken.

Nowadays weapons have been made in the world that were not operational at any war and modern countries claim that these weapons are capable of destroying underground structures. Therefore, in regard to this explanation and the need to defend, dynamic designing of underground structures against special bomb blast seems to be indispensable. Wave propagation in stone mass which are inherently inconsistent and have variable behavior and dynamic designing of underground structures that are established in stone mass as well, are very complex. In many studies conducted to wave propagation in stones, the earth has been considered as a homogeneous, similar and completely elastic environment, whereas the earth has an inconsistent nature and its behavior is not compatible with the said conditions at all. In this regard, the study of the real earth behavior against wave propagation seems to be necessary. This paper makes use of UDEC software which is based on component element method and has the ability to dynamically analyze inconsistent stone environments to study loading, wave propagation and damping caused by surface explosion which culminated in desirable results.