The high-frequency performance of the reflector antennas is mainly limited by the surface. It has been shown that distortions on different regions of the reflector surface can have different effects on the radiation performance. In other words, degradation of the radiation pattern due to the presence of surface distortions is sensitive to the location and behavior of the surface distortion profile. In this paper, the concept of "sensitivity of the radiation pattern to the surface distortion" has been introduced and quantified. It can be used in the design of different reflector antennas to prevent radiation degradations due to surface distortion. Based on the Physical Optics and variational analysis, the first-order variational of the far-fields with respect to the surface profile is formulated to present the concept of sensitivity. The variational amplitude can be modified to show the concept of sensitivity of the radiation pattern to the distortions on the surface. Reflector antennas with different geometries and feeding methods have different sensitivity plots. Both co- and cross-polarization fields for feed antenna are considered ti be used in the symmetric and offset reflectors, and sensitivity plots are extracted. Sensitivity plots show areas on the surface that have stronger effects on the radiation pattern variations in the region of the main-lobe and the first few side-lobes.

In this research, we used daily incoming solar radiation data of Isfahan ozone station during 1365-1387 to find an estimation model of Incoming solar radiation using sunshine ours. The results have been compared to the other common models using RMSE and MBE indices. The results show that the regression amount of our model is 0.91 and 0.6 and 0.7 for the models Frere and McCulloc respectively. Also, our model has a very precise results for May and Augest months in which the error is less than -2 %.

Solar radiation is the most important meteorological element which affects all climatological and biological processes such as evaporation and transpiration, snowmelt and plant growth directly and indirectly. Various planning in agriculture, hydrology, architecture and energy largely depend on the correct estimation of the amount of solar radiation. One of the most accurate methods in measuring solar radiation is using pyranometer which its usage is still limited in many parts due to the lack of facilities. Consequently, the researchers are trying more to estimate the radiation, instead of directly measuring it. Most of the previous studies have used Angstrom model, having the values of sunshine hours as its input, or regression equations through considering the climatic factors and elements affecting the radiation, to estimate the solar radiation. The aim of this study is to estimate and evaluate the spatial-temporal changes of receiving solar radiation in Kermanshah Province by using the "Bird and Hulstrom" model...

One of the most common methods used in radiation therapy for the treatment of superficial skin lesions using the ortho-voltage radiation X (the kVp 300), respectively. One of the most important indicators for the treatment of this type of device, the quality of the X-ray output is usually half the thickness of the absorption (HVL) Vanrzhy show photons effective. However, in this study, the coefficient of homogeneity was examined as a factor. Materials and Methods: In this study, the half-absorption layer (HVL) and homogeneity coefficient of the X-ray surface voltage was determined kV180 experimental and simulated with Monte Carlo method and the results were compared with the EGSnrc code. Using the measured absorption curve for this exposure through the layers of the weakening of the clinic was drawn with appropriate interpolation of the curve, the half-absorption layer (HVL) and homogeneity coefficient, respectively. The package EGSnrc, the code BEAMnrc to simulate photon and electron transfer up to receive daily intravaginal and BEAMDP for coefficient homogeneity systematically and draw the output spectrum (using data from phase space code BEAMnrc) and the code DOSXYZnrc to trace the curve of percentage depth dose the water phantom was used. The results show that the mean percentage difference between the HVL and homogeneity coefficient obtained from simulation and experiment 2, 96.4% and 01.3%, respectively. Conclusion: According to previous studies that measured HVL of difference between experimental and simulated 2% to over 10% were reported as the mean difference between the 96.4%, respectively. The difference is that this is reasonable. Homogeneity coefficient was calculated from the above previous reports due to differences in the code is justified. Considering the limitations of the clinics, the present method because of the simplicity of the layout and the similarity of the clinical conditions seem to have good performance.

Background and Aims: When composite resin polymerizes, shrinkage stresses tend to produce gaps at the tooth/ restoration interfaces. surface sealants may reduce or avoid problems related to the marginal interface. The aim of this study was to evaluate the effect of two different surface sealants (Fortify and Optiguard) on the microleakage of class V resin composite restorations.Materials and Methods: Twenty three sound noncarious molars were collected. Totally, 45 Class V cavities with the occlusal margins in enamel and cervical margins in cementum were prepared in both buccal and lingual surfaces. The specimens were randomly assigned in three groups (15 cavities in each group) and then restored with a resin composite. After the finishing and polishing procedures, the restorations in each group were covered with a specific surface sealant, except for the control samples, which were not sealed. After placing restorations, the specimens were thermocycled and then immersed in a 50% silver nitrate solution (tracer agent) for four hours, sectioned longitudinally and analyzed for leakage using a stereomicroscope in a blind manner. The marginal microleakage was evaluated at the occlusal and cervical interfaces and compared among the three groups using the Kruskall-Wallis and the Mann-Whitney U tests.Results: Microleakage was found in all groups at both occlusal and cervical margins. Significantly greater leakage was observed at the cervical margins compared to the enamel margins of the material groups (P=0.005).There was no statistically significant difference among the groups at occlusal margins (P=0.66). In the cervical region, Fortify showed improved results and statistically presented the lowest degree of microleakage (P=0.003).Conclusion: The used sealant materials presented different rates of effectiveness and Fortify decreased marginal microleakage significantly.

Reducing the amount of radiated energy from military equipment such as helicopters leads to an increase in the     possibility of hiding or camouflage them. In this study, the parameters affecting radiation heat transfer, including heat transfer equations, the effects of diffusion environment, the heat flux reaching the surface of the helicopter body, and the geometry of the helicopter body surface are investigated. Then, software simulation is performed in the presence of sunlight and at different angles and its effect on thermal sensors. The results obtained from the simulation show that the angle of the helicopter and the absorption coefficient are the effective characteristics in thermal radiation. By changing the angle of the helicopter, the visibility coefficient between the sensor and the helicopter changes, and as a result, the amount of radiation in between also changes, and these changes also change with the change in color,   material, surface and other factors affecting the absorption coefficient.