Construction of a standard test assembly for controlled laser studies in tissues: preliminary study on human bone material

Measurements error propagation and its sensitivity analysis in the aero-engine multistage rotor assembling process

The purpose of this paper is to research the measurements error propagation principle about the measurement-assembly equipment of aero engine multistage rotor, besides analyze the effect of guide linear motion and turntable rotational motion on the final alignment error. Furthermore, we can improve the measurement and assembly accuracy of the aero engine multistage rotor. In this paper, a novel error analysis method related to measurement-assembly equipment was proposed. First, the topology of the measuring equipment was established based on the multibody system theory, the error propagation path was constructed by using the low order body sorting method. Second, the error transfer model of the linear motion and the rotational motion were established by using the homogeneous coordinate transformation matrix, and the total measurement terminal errors introduced by the equipment were calculated. Finally, through numerical simulation, the magnitude of the measurement terminal offset error was obtained, sensitivity analysis was performed to calculate key error sources. Measurement accuracy not only depended on the accuracy of the sensor but also closely related to the accuracy of the measurement-assembly equipment. Through the simulation verification, when the linearity error is 0.1 μm and the angular error is 0.1″, the final cumulative offset displacement error is about -0.1002 μm to -0.0998 μm with a probability of 97%. Different type errors have different effects on the results. We can give a conclusion that linear guide alignment error and verticality error are the primary error sources, and the angle error of the turntable need to be improved.

The influence of water/air cooling on collateral tissue damage using a diode laser with an innovative pulse design (micropulsed mode)-an in vitro study

Since the diode laser is a good compromise for the daily use in dental offices, finding usage in numerous dental indications (e.g., surgery, periodontics, and endodontics), the minimization of the collateral damage in laser surgery is important to improve the therapeutical outcome. The aim of this study was to investigate the effect of water/air cooling on the collateral thermal soft tissue damage of 980-nm diode laser incisions. A total of 36 mechanically executed laser cuts in pork liver were made with a 980-nm diode laser in micropulsed mode with three different settings of water/air cooling and examined by histological assessment to determine the area and size of carbonization, necrosis, and reversible tissue damage as well as incision depth and width. In our study, clearly the incision depth increased significantly under water/air cooling (270.9 versus 502.3 μm-test group 3) without significant changes of incision width. In test group 2, the total area of damage was significantly smaller than in the control group (in this group, the incision depth increases by 65 %). In test group 3, the total area of damage was significantly higher (incision depth increased by 85 %), but the bigger part of it represented a reversible tissue alteration leaving the amount of irreversible damage almost the same as in the control group. This first pilot study clearly shows that water/air cooling in vitro has an effect on collateral tissue damage. Further studies will have to verify, if the reduced collateral damage we have proved in this study can lead to accelerated wound healing. Reduction of collateral thermal damage after diode laser incisions is clinically relevant for promoted wound healing.