The Effect of Beam Direction on Absorption and Transmission of Ultraviolet to Infra-red Wave-length in Three Different Dentin Thicknesses

BackgroundsLasers and optics have extensively been used in dental procedures in recent years, so realizing the optical properties of the tooth represents a milestone in its successful applications. the aim of this study was to compare the absorption and transmission of applied wavelengths in 190-1100 nm range in various dentin thicknesses and the effect of changing the direction of beam emission in dentinal tubules.MethodsFifteen dentin specimens with a thickness of 300, 600, and 1000 µm and five specimens from each thickness were prepared by a transverse incision at the upper pulpal roof area of the human molars.Considering the Corono-apical and Apico-coronal direction, we measured the absorption and transmission of parallel light beams perpendicular to the dentin specimens in various thicknesses and two directions using a UV/ Visible spectrometer.ResultsThe ultraviolet wavelength's absorption rate was significantly higher than visible and infrared light irradiation from both directions in three thicknesses (p-value<0.001). Additionally, The radiation beam displacement had no significant differences in the absorption and transmission of ultraviolet, visible, and infrared light in any of the three thicknesses (p-value>0.05).ConclusionAccording to the results, the change in the beam direction during irradiation does not cause a significant difference in light absorption. Furthermore, the results are expected to develop a suitable method for evaluating the trans-dental performance of different optical parameters for diagnostic purposes in the dental tissues.

Robust squeezed light against mode mismatch using a self imaging optical parametric oscillator

We present squeezed light that is robust against spatial mode mismatch (beam displacement, tilt, and beam-size difference), which is generated from a self-imaging optical parametric oscillator below the threshold. We investigate the quantum properties of the generated light when the oscillator is detuned from the ideal self-imaging condition for stable operation. We find that the generated light is more robust to mode mismatch than single-mode squeezed light having the same squeezing level, and it even outperforms the single-mode infinitely squeezed light as the strength of mode mismatch increases.

Fracture of Electron Beam Welding Joints of Titan Alloys

Analysis of fracture surfaces morphology of material of welded joints of Ti-TiB system alloys and (α + β) Тi alloy, obtained by electron-beam welding under various technological modes, is carried out. Parameters alterable were the electron beam displacement velocity and initial temperature of the parts welded. Prevalent effect of boron phase on fracture character of Ti-TiB system alloys and possibility of ductility increase both Ti-TiB system and (α+β Тi alloy, due to thermal effect action, is shown.

A force measuring microsystem bases on electrothermal V-shaped actuator

This paper describes design and calculation of an electrothermal V-shaped actuator (EVA) and an amplification mechanism integrated into a force measuring microsystem (FMMS), aims to apply for characterization of a micro beam. Displacement and driving force are generated by thermal expansion of the V-shaped silicon beams while applying a voltage to the electrodes of the EVA. ANSYS simulation helps to find out the relations between thermal force and displacement corresponding to driving voltage and determine the temperature of V-shaped beam at various applying voltages. In our simulation, with applying voltage Um = 38 volt for six pairs of V-shaped beam, the maximal temperature of the beam reaches approximately to 1100°C and causes a melting phenomenon of the silicon beam. The additional amplification mechanism allows actuator's displacement to be 6 times larger than before the improvement, thus the bending deformation of the micro beam can be seen perfectly, i.e. the force loading on the beam can be computed more exactly via a measured displacement of the beam tip. In addition, this FMMS has smaller size and supplies a larger beam's deformation at the same voltage in comparison with previous design.

The assessment of soil depth sensitivity to dynamic behavior of the Euler-Bernoulli beam under accelerated moving load

Dynamic behavior is one of the most crucial characters in the railways structures. One of the items which leads to precise identification of the dynamic behavior of railways is the soil depth beneath them. In this paper, an Euler-Bernoulli beam on a finite depth foundation under accelerated moving load is presented. The dynamic equilibrium in the vertical direction is only regarded in accordance with the factor of finite beams. In this study, the dynamic equilibrium of the soil in the vertical direction and the sensitivity of soil depth are considered. The governing equations are simulated by using Fourier transform method. Eventually, by considering the sequences of shear waves, and different kinds of damping, displacement of the beam is obtained for the various acceleration, times and soil depth. As a result, it is shown that, higher acceleration is not dramatically effective on the beam displacement. Also, foundation inertia causes a significant reduction in critical velocity and can augment the beam response.