Development and Verification of Desktop Printed 3-Dimensional Guides for Angulation and Depth Controlled Conservative Endodontic Access

Introduction: Recent studies have shown that conservative endodontic cavities (CECs) have a higher mean load at fracture in molars and premolars compared to traditional access cavities, however, performing these CECs can be challenging for the practitioner. Microguided endodontic access is a reliable means of preserving dentin while gaining access to the pulp chamber. The aim of this study was to 1. Develop a protocol for designing angulation and depth controlled physical guides to perform endodontic access, and 2. To compare its ability to provide straight line access against a decoronated tooth, measuring angle of deflection of inserted files. Materials and Methods: With use of both Kodak Carestream 9000® CBCT scans and Planmeca PlanScan® intraoral scans of acrylic blocks containing extracted teeth, depth and angulation controlled guides were designed with the Planmeca Romexis implant planning software and printed with a Formlabs 2 3D printer. A total of 23 teeth (totaling 76 canals) were accessed using a #4 surgical length round bur with the guides in place. Results: Subjective analysis confirmed passive straight line access with a #6 C file through the CECs for all canals and CBCT images were captured. The imaging was repeated with files in the canal after the teeth were decoronated. Difference in angle of deflection of the files were measured between the 2 models, confirming the clinical finding of passive straight line access. The average file angle deviation was 1.98 ± 1.06° for all canals. No significant differences were seen between tooth types in each arch, nor between arches. File deviation ranged from 0.23° to 5.28°. Conclusion: A protocol was successfully developed to accurately and reproducibly create 3D printed guides for conservative fully-guided endodontic cavity preparation

Influence of inlet geometry on the efficiency of 1 MW steam turbine

The process of the design of the 1 MW steam turbine includes designing the stator and rotor blades, the steam turbine inlet and exit, the casing and the rotor. A turbine that operates at rotation speeds other than 3000 rpm requires a gearbox and generator with complex electronic software. This article analyses the efficiency of eight turbine variants, including seven inlet geometries and three stages of stator as well as an eight variant with one of the inlets, all three stages and an outlet. This article analyses the efficiency of 8 turbine variants, including four spiral inlet geometries and tree stages in a 1 MW steam turbine. In the article, inlets and 1st stator blades of various geometries were analysed to obtain maximal turbine efficiency. Changing the inlet spiral from one pipe to two pipes increased the turbine efficiency. The geometry of the blades and turbine inlets and outlet was carried out using Design Modeller. The blade mesh was prepared in TurboGrid and inlet in ANSYS Meshing

Various inlet spiral geometries in 1MW steam turbine

In small turbines, inlets can be designed using an inlet spiral. This paper analyses the efficiency of eight turbine variants, including seven with three stator and rotor blades and inlet spirals of various geometries, and one variant with a spiral, three stages and an outlet. This involves a 3D steady viscous flow using ANSYS CFX. The analysis shows that the spiral has a considerable influence on turbine efficiency

Tip-timing analysis of last stage steam turbine mistuned bladed disc during run-down

This paper presents the experimental and numerical studies of last stage LP mistuned steam turbine bladed discs during run-down. The natural frequencies and mode shapes of the turbine bladed disc were calculated using an FE model. The influence of shaft was considered. The tip-timing method was used to find the mistuned bladed disc modes and frequencies. The numerical results were compared with experimental ones

Tip-timing analysis of last stage steam turbine mistuned bladed disc during run-down

This paper presents the experimental and numerical studies of last stage LP mistuned steam turbine bladed discs during run-down. The natural frequencies and mode shapes of the turbine bladed disc were calculated using an FE model. The influence of shaft was considered. The tip-timing method was used to find the mistuned bladed disc modes and frequencies. The numerical results were compared with experimental ones

New blade tip-timing system for measuring rotor blade vibration of steam and gas turbines

One of the crucial issues regarding turbine maintenance is registering blade vibrations. These vibrations can cause serious damage to the engine. Turbine blade vibrations were measured during nominal speed as well as during run up and run down. A new, low cost Blade Tip Timing (BTT) is presented in this paper. It composes of two main modules: the FPGA unit and PC unit. The system is based on the TerasIC DE0-CV development board controlled by the Cyclone V 5CEBA4F23C7 chip. Units communicate via an Ethernet interface. The system measures a signal for every revolution as well as up to three signals coming from independent rotor blade sensors. The PC unit records these data in .csv files. The system can be adapted to process the signals of additional sensors. The measurements of the 1st stage compressor blade vibrations in an SO-3 engine prove that the system works correctly, with no data loss during transmission between system units, and compares well with other measurement systems as well as numerical results