In this paper, an adaptive BEAMforming algorithm is introduced. In this algorithm 2M2+7M multiplications are needed in every vector sample which M is the number of the array elements. It is possible to reduce the number of the multiplications to 5M if more simplifications are done which is suitable for practical applications. In this method, adaptive algorithm is applied in pattern space and the RATIO of the main BEAM to the INTERFERENCE BEAM greater than 50dB is obtained which is acceptable in the considered environmentwith 6dB of SINR.

Background and Objective: The aim of this study was to evaluate the diagnostic ability of CBCT to detect external root resorption.Subjects and Methods: External root resorption defects of different sizes and in different locations were simulated in 60 human mandibular incisors. Cavities simulating root resorption defects of small size (0.3´0.6 mm), medium (1.2´0.6 mm) and large (1.8´0.9 mm) were drilled in the cervical, medial and apical thirds of buccal surfaces. The teeth were divided in random groups and mounted in the mixture of acryle and dryed skull sheep powder. CBCT scan was used to evaluate external root resorption in 180 root thirds by two blinded observer. Statistical analysis was done with Kappa test.Results: Sensitivity of CBCT to detect external root resorption was 89% and the specificity was 99 %.The most defects that was detected were on the medial root thirds and the lowest defects that were detected were on the apical root. The percentage of small defects detection was 80%.Conclusion: CBCT technique is a very good method to evaluate external root resorption with high sensitivity and excellent specificity. It can detect the defects as small as 0.3mm.

This paper investigates damping RATIO in micro-BEAM resonators based on magneto-thermo-elasticity. A unique aspect of the present study is the effect of permanent magnetic field on the stiffness and thermo-elastic damping of the micro resonators. In our modeling the theory of thermo-elasticity with interacting of an externally applied permanent magnetic field is taken into account. Combined theoretical and numerical studies investigate the permanent magnetic field effect on the damping RATIO in clamped-clamped and cantilever micro-BEAMs. Furthermore, the influence of the magnetic field intensity on the frequency of the micro-BEAMs with thermo-elastic damping effect is evaluated. Such evaluations are used to determine the influence of magnetic field on the vibRATIOn amplitude of the resonators. The meaningful conclusion is that the magnetic field increases the equivalent stiffness and thermo-elastic damping and consequently the energy consumption of the resonators.

In this paper, an alternative approach in opeRATIOnal modal analysis is presented, utilizing image processing technique and transmissibility functions. Imaging sensors do not impose additional mass on the structure due to their non-contact nature, while transmissibility functions, independent of excitation type, can directly extract mode shapes. The innovation of this research lies in combining these two techniques to record dynamic responses and identify modal properties. To capture the temporal response history from video signals, the block-matching method with sub-pixel accuracy was employed. Validation was conducted by recording the response of the tip of a cantilevered steel BEAM subjected to impact excitation, using a high-speed camera and a laser vibrometer, simultaneously. The RMSE plots in the time domain and the PSD in the frequency domain indicate high accuracy of this method. Using this approach, the displacement time histories of various points on the structure were extracted from the video signals, and the modal properties, including natural frequencies, damping RATIOs, and mode shapes, were identified using the transmissibility matrix method. The results obtained from the proposed method were compared with the stochastic subspace identification (SSI) method and analytical solutions. The findings reveal the accuracy of the modal identification approach introduced in this article. The highest relative error in estimating the natural frequencies of the first and second modes, compared to the values from the laser method, are 0.19% and 0.13%, respectively, and in comparison to the analytical values, they are 0.34% and 1.5%, respectively.

Background & Aims: The aim of this study was to evaluate the accuracy of Cone-BEAM Computerized Tomography (CBCT) linear measurements in dry mandibles by comparing them with direct measurements.Methods: Two human dry mandibles were used in this study. Thirteen sites were selected on each mandible. Specimens were scanned by CBCT and linear measurements were made using Planmeca Romexis 2.3.0.R software. Mandibles were cut into sections at marked locations and the same distances were measured by a digital caliper. Differences between two methods were assessed using paired t- test.Results: The mean differences for bone height, bone width and the crest-canal distance between CBCT and digital caliper measurements were -0.47±1 mm, -0.14±0.78 mm and 0.00±0.76 mm respectively. The differences were only, significant for bone height measurements (P<0.05). There was a high carreltion between the result of CBCT and gold standard.Conclusion: The results of this in-vitro study on mandible indicate that, although there is a statistically significant difference for bone height measurements between the two methods, the difference is not significant in clinical applications. Thus, CBCT was shown to be a useful technique for preoperative dental implant planning.

Background and purpose: BEAM shaper is a type of applicator used in conjunction with the intraoperative electron radiotherapy. This study aimed at quantitative evaluation of the photon contamination of this applicator using Monte Carlo simulation.Materials and methods: In this experimental study, at first the head of LIAC accelerator was simulated along with the BEAM shaper applicator using MCNPX Monte Carlo code. Validity of the simulated model was evaluated by comparing the percentage depth dose curves obtained by Monte Carlo simulation and practical dosimetry. Finally, the photon contamination at different clinical field sizes and electron energies was quantitatively determined.Results: The results showed that by increase in field size, the photon contamination of the BEAM shaper applicator was considerably decreased. Furthermore, increment of electron energy could increase the photon contamination.Conclusion: Increasing the photon contamination at the phantom surface by increment of electron energy and decrement of field size can be attributed to increasing the probability of electron interaction with the steel blades of the BEAM shaper and production of bremsstrahlung radiation at higher energies. Due to the photon contamination, employing the BEAM shaper applicator can increase the surface dose.

Background and Aim: BEAM shaper applicator is one of the dedicated applicators for intraoperative electron radiotherapy which is usually employed for large tumors irradiation. Due to the high weight and lack of possibility of direct placement on the patient’ s body, a considerable air gap exists between the applicator and patient. Therefore, determination of the effective position of electron source (SSDeff) is absolutely necessary to correct the applicator output for air gap effect and accurate delivery of the prescribed dose to the patient. The aim of this study was to determine the SSDeff for all square fields of BEAM shaper applicator at different electron energies using Monte Carlo (MC) simulation. Materials and Methods: At first, the head of LIAC accelerator and BEAM shaper applicator were simulated by MCNPX MC code and then, the validity of the simulated model was evaluated through comparing the calculated percentage depth dose (PDD) curves at different field sizes and energies with the corresponding practiacal values. After verifying the simulated model, the SSDeff was determined for different field sizes and electron energies using inverse square law (ISL) method. Results: The results showed that the SSDeff is a function of electron energy and radiation field size. Dependency of SSDeff on field size variations was much more than that on the alteRATIOns in the electron energy. Generally, increase in the field size or electron energy led to increase in SSDeff. Conclusion: The determined SSDeff values for the electron BEAM of the BEAM shaper applicator in our study, can be used to correct the electron BEAM output for clinical purposes.

The aim of this paper is to study the influence of the column-to-BEAM strength RATIO on the seismic strengthening of a column with a Fiber-Reinforced Plastic (FRP) wrapping system. FRP wrapped Reinforced Concrete (RC) columns are analyzed to obtain moment-curvature curves using FRP confined concrete characteristics. A pushover analysis of a 2D model was performed on one and three-story moment-resisting frames, with different column-to-BEAM strength RATIOs. The results indicate that FRP strengthening is more efficient in frames with a low RATIO of column-to-BEAM strength, due to the type of lateral failure mechanism of the frame. Also, high values of the column-to-BEAM strength RATIO can be benefited by low values of the confining pressure. In case of column strength greater than BEAM strength, beyond a certain confining pressure RATIO, further enhancement in performance will not be achieved. Therefore, the level of effective wrapping on frame performance enhancement is controlled by the column-to-BEAM strength RATIO.