Investigating the possibility of detection of the concealed military structures is one of the complicated problems. This structures is created a significant conductivity in opposite of the earth which can be detected using ELECTROMAGNETIC method. AIRBORNE ELECTROMAGNETIC method is considered as an important geophysical method that is used in the AIRBORNE survey. This method is characterized by high speed, extensive coverage, cost-effective and performance capabilities for implementation in sever topographical relief. In this paper, we used ELECTROMAGNETIC data to solve the problem. In order to analyze this problem, both forward and inverse problems are treated in this contribution. In the forward problem, with the assumption of the known size and position of the structure, secondary magnetic field signal is modeled. Then, using the modeled signals, some points about the detectability of the structures are discussed. Finally, both of the forward and inverse problems are implemented based on simulated data and some suggestions are made to decrease the probability of detectability of the underground military targets.

There is a set of variables affecting the results of an inversion process. Some effects are negligible while others are significant. It is important to know these essential variables to set them appropriately. In this study, the effect of change in the number and the thickness of the layers, the trade-off parameter, the number of frequencies and frequency content of the signals used for the inversion are studied. Occam’s inversion is employed to reconstruct the resistivity and/or conductivity of the assumed layers.The thickness and number of layers can affect the recovered model. The best way to choose the number of layers is to increase it until the fitness error flattens. The error decreases, significantly with the inclusion of the first additional layer then in increasingly lesser degrees with subsequent additions, until it reaches a relatively constant level. The number of layers at which it first reaches this constant level is assumed to be the best number. As the number of layers is increased, the original model is modified slightly. On the other hand, the EM signal strength drops exponentially with distance. Hence, it is better to increase the thickness of the lower layers to overcome this decrease. Experience shows that logarithmically increasing thicknesses result in better models. However, if the sufficient number of layers has been chosen, the change in thickness cannot affect the recovered model significantly because a thick layer can be estimated as a sum of thinner layers.The trade-off parameter has a critical effect on model parameters. It controls whether more weight is given to minimize the norm of the data misfit or model norm. When this parameter is large, the inversion process tends to produce a smoother model and the data misfit becomes less important. On the other hand, when it is small, the data misfit takes over regardless of a priori information. Generally speaking, the best trade-off parameter is considered to be that at which the data fit is satisfying. The results of this paper show that the effect of the changes on the trade-off parameter is significant and if one chooses it inappropriately, the estimated model will fail to represent the true model.It is clear that the inversion response depends on the number of data used. The more data used, the better the model produced. The values of frequencies used are also important because high frequency data can have information only about surface layers while low frequency data have more information from deeper layers. The effect of the number and values of the frequencies was studied by changing or removing high/low frequency. The results show that the change in frequency content causes a considerable effect on the resolution of inversion.We also studied the effect of the changes of these parameters on the results of inverting a real data set and the results confirm the effects described in the models recovered.In brief, we can say that the effects due to changes in the number and the thickness of layers are negligible, but the effects of changes in the trade-off parameter and the number of frequencies are significant.

The electrical behavior of neurons can be more complex in the presence of autapse. In the presence of an autaptic connection, the Izhikevich neuron model can show a variety of dynamic behaviors, such as chaotic behavior. This paper presents a novel, high speed and robust pseudo random number generator based on the autaptic Izhikevich neuron oscillator and its FPGA implementation. The autaptic Izhikevich neuron model is simulated and dynamically analyzed. Then, the proposed pseudo-random number generator is modeled and simulated using the Xilinx system generator platform, synthesized using Xilinx Synthesis Tool, and implemented on the XILINX SPARTAN-6 XC6SLX9 FPGA evaluation board. As a post processing operation, the XOR function is used to increase the randomness of the output bit sequences. The FPGA implementation results show that the implementation cost of the proposed pseudo-random number generator is lower than similar works, and the proposed generator achieves a maximum frequency of 63.2 MHz. The NIST test suite is used for testing the quality of the generated bit sequences. The NIST test results indicates the high quality of the generated random bit sequence.

AIRBORNE ELECTROMAGNETIC data can be obtained in time and frequency domains. In time domain, data consist of the time derivative of the secondary field while in frequency domain it is the absolute value of the secondary field. Here, we have used Occam’s inversion method on AIRBORNE ELECTROMAGNETIC data to resolve the resistivity of each layer in an assumed 1D layered earth. In the current modeling the number of model parameters is much more than the number of data. So, by choosing an appropriate objective function to be minimized, we have used the least squares method such that model parameters reached to a minimum structure and data are sufficiently fitted. One of the advantages of this method is that it doesn’t need a primary model and converges to the final model for every starting model. Applying this method on synthetic data provides reasonable results. The method is applied on real AIRBORNE ELECTROMAGNETIC data from Kalat-e-Reshm area in the east of Semnan province in Iran. The recovered maps and sections prove the existence of an arc like structure which has outcrop at the surface and is shown in the geological map. Besides, it reveals that the structure is considerably thick due to the alluvium deposits with 10 m thickness covering the area with a dip towards south.

Background: Occupational risk of dental personnel to microbial AIRBORNE contamination has been demonstrated through the increased prevalence of respiratory infections. The American Dental Association has suggested stringent protection for infectious agents present in dental aerosols.Materials and Methods: Occupational exposure of dentists to AIRBORNE microbial and mycological contamination in various locations of a dental school was monitored by sampling of air in close vicinity of their breathing zone. This sampler drew air at a flow rate of 10 liters/minute and for a 2-hour period and blew it at a high speed through a narrow slit over a solid nutrient agar plate. Immediately after sampling, the plates were placed in an incubator and incubated aerobically for 2 days at 37°C. Results: The total bacterial counts in the air of dental surgery rooms and in non-surgery rooms without direct involvements with dental operations were in the range of 120-280 cfu/m3 and 49-128 cfu/m3 respectively. Pathogenic Streptococcus haemolyticus and opportunistic Staphylococcus species were found in some locations of dental surgery rooms.Conclusion: There are no standards for acceptable levels of indoor air contamination with pathogenic microorganisms and since pathogenic Streptococcus haemolyticus and opportunistic Staphylococcus species were found in some areas of the dental school, the need for management of possible risk of infective hazards is recognized.

Background: Air contamination with fungal spores and the presence of these spores on respiratory tract, especially in industrialized cities with contaminated air, can play an important role on the occurrence of respiratory and coetaneous mycoses, asthma and allergic reactions. This survey was carried out to determine the prevalence of different fungal spores in the atmosphere of Tabriz district. Objectives: The present study aimed to detect fungal air spores in Tabriz environments, and to compare the environmental samples of Aspergillus fumigatus with the clinical isolated samples of this fungus, due to the importance of the dangers of A.fumigatus for public health, particularly for the immunocompromised patients. Materials and Methods: During this survey, the presence of air fungal spores was analyzed using settle plate and prepared culture in Sabouraud's dextrose agar. Prior identifications were performed using macroscopic characters, and direct microscopy. 262 samples were collected from different areas of the atmosphere of Tabriz district within all four seasons of the year. Fungal colonies were isolated from all air samples and identified using macroscopic and microscopic characters, and slid culture. Results: The main isolated fungal spores from the atmosphere of Tabriz district were Penicillium Sp. (36.6%), Cladosporidium Sp. (26.8%) and Aspergillus Sp. (23.6%). Conclusions: The presence of fungal spores in the atmosphere as a part of air pollution can cause significant problems for human health, particularly in the respiratory tracts.

Typical VLF data exhibit considerable 2D effects and 2D inversion offers several advantages when applied to profiles of VLF data. First it provides a quantitative estimate of the basement conductivities away from conductors. Secondly the relation between real and imaginary parts of the tipper vector provides information about the depth of the major conductors giving rise to the anomalies. In this paper, a synthetic model of a vertical contact and a profile of AIRBORNE VLF data are discussed.