objectives: the purpose of this study was to develop and test a new tool for radiographic densitometry by combining periapical films and aluminum step wedge. materials and methods: we reviewed 50 kodak e-speed intraoral films. an aluminum step wedge consisting of 16 steps was constructed. each step was 1mmx3mx10mm. the step wedge was exposed to varying exposure times, ranging from 0.05 second t...

The equations of motion for pressure and displacement fields in a waveguide have been used to derive an energy-conserving, one-way coupled mode propagation model. This model has three important properties: First, since it is based on the equations of motion, rather than the wave equation, instead of two coupling matrices, it only contains one coupling matrix. Second, the resulting coupling matr...

Surface plasmon modes at terahertz-infrared waveband in subwavelength graphene wedge and groove waveguides are investigated, which can be categorized into perfect electric conductor and perfect magnetic conductor symmetric modes with different propagation characteristics. The electromagnetic near-fields are localized strongly in different regions for these two kinds of modes. Moreover, these mo...

A new transducer beam model is developed for the generation of Rayleigh surface wave and Lamb plate waves by an angle beam transducer, which is one of the configurations commonly used for the generation of these wave types. The beam model is a fully 3-D model that takes into account the fields generated by the transducer acting on the surface of a wedge. The model also accounts for the leaky wa...

This article compares two algorithms for determining beam weights and wedge filters for conformal treatment planning. One algorithm, which is based on dose-gradient analysis, provides analytic formulas for determining beam weights, wedge angles, and collimator angles (i.e., wedge orientations) so that the dose distribution is homogeneous in the target volume. The second algorithm is based on th...

Several recent reports have described methods for calculating enhanced dynamic wedge factors (EDWFs). Many of these reports use the monitor-unit (MU) fraction method to predict EDWFs as a function of field size. Although simple in approach, MU fraction methods do not produce accurate EDWFs in large or asymmetric fields. A recently described technique, based on the MU fraction method works well ...

We studied the drag and lift forces acting on an inclined plate while it is dragged on the surface of a granular media, both in experiment and in numerical simulation. In particular, we investigated the influence of the horizontal velocity of the plate and its angle of attack. We show that a steady wedge of grains is moved in front of the plow and that the lift and drag forces are proportional ...

The geometrical theory of diffraction (GTD) provides a powerful and computationally efficient framework for investigating real-world diffraction problems. Originally restricted to perfectly electrically conducting (PEC) wedges, the GTD and its uniform offspring have since been extended to wedges characterized by impedance surfaces (R. Tiberio et al., IEEE Trans. AP, 37, 2, 212-218, 1989). Thoug...