A dynamic model for inertia energy stored generator with rectifier system
Due to diode elements, inertia energy stored generator with rectifier system possess the characteristic of nonlinearity, which cause great difficulty in analyzing systematic performance. In this paper, The inertia energy stored generator is modeled based on the fact that subtransient electric motive force (EMF) maintain constant during commutation process, and the uncontrollable rectifier system is also modeled based on state space averaging method. Both of which provide an effective model for systematic analysis.
Small-signal Stability Studies of a 270V DC More-Electric Aircraft Power System
The paper investigates the small-signal stability of a representative 270V DC power system for a more-electric aircraft, which incorporates a switched reluctance generator, under various operation conditions, including power control saturation due to current and voltage limits. Non-linear state-space models for the complete system under the various operating conditions are established, and the eigenvalue method is applied to assess the small-signal stability. Time-domain simulations are used to validate the findings of the proposed analysis technique.
Assessment of fractures in endodontically treated teeth restored with and without root canal posts using high-resolution cone beam computed tomography
Background Root fractures are a diagnostic challenge for dentists in endodontic treatment. This study aimed to determine the relationship between the characteristics of tooth fractures and the presence of root canal posts in endodontically treated teeth using high-resolution cone beam computed tomography (CBCT). Material and Methods Fifty high-resolution CBCT scans of endodontically treated teeth with a diagnosis of fracture were obtained, of which 30 were from women and 20 were from men. These scans were acquired with three Veraviewepocs 3D units and one 3D Accuitomo 170 unit, with a 40 × 40-mm field of view and 125 μm voxel size. The variables assessed included the type of fracture, extent of fracture, type of retention, post length, cause of endodontic failure, location of the lesion, and time required to detect the fracture (difficulty score). For data analysis, the chi-squared test, Student’s t-test, and multiple linear regression (α <0.05) were used. Results No association was found between the type of fracture and type of retention or between the type of fracture and its extent (P>0.05). On the other hand, the type of fracture significantly influenced the time required for its detection. Additionally, the most difficult plane for detecting the fracture and the difficulty score were associated, with statistically significant results. Conclusions The type of fracture in endodontically treated teeth was not associated with the type of post used for restoration. All of the CBCT systems used to detect tooth fracture showed the same efficiency. Key words:Cone-Beam CT, Tooth Fracture, Root Canal Post.