DENTOMAXILAR DISCREPANCY AND CROWDING. LITERATURE REVIEW

Dentomaxillary anomalies are alterations in the spatial relationships between teeth teeth and their maxillary bone bases that in most cases “result from a relative discrepancy between the size of the teeth and the bones, regarding the analysis of the discrepancies, we can find that the teeth could be associated with the appearance of diastemas (in case the discrepancy is positive), crowding (when the discrepancy has a negative value) or a discrepancy in tooth size, called a discrepancy of Bolton. This review emphasizes the importance of including these measurements in the diagnosis in order to avoid a result with a poor predictable future.

Robustness of Empirical Vibration Correlation Techniques for Predicting the Instability of Unstiffened Cylindrical Composite Shells in Axial Compression

Thin-walled carbon fiber reinforced plastic (CFRP) shells are increasingly used in aerospace industry. Such shells are prone to the loss of stability under compressive loads. Furthermore, the instability onset of monocoque shells exhibits a pronounced imperfection sensitivity. The vibration correlation technique (VCT) is being developed as a nondestructive test method for evaluation of the buckling load of the shells. In this study, accuracy and robustness of an existing and a modified VCT method are evaluated. With this aim, more than 20 thin-walled unstiffened CFRP shells have been produced and tested. The results obtained suggest that the vibration response under loads exceeding 0.25 of the linear buckling load needs to be characterized for a successful application of the VCT. Then the largest unconservative discrepancy of prediction by the modified VCT method amounted to ca. 22% of the critical load. Applying loads exceeding 0.9 of the buckling load reduced the average relative discrepancy to 6.4%.

Profiling with Depth Resolution of Sub-nm for SiO2/ SiC Interface by Dual-Beam TOF-SIMS Combined with Simulation

For precise investigation of distribution for impurity or composition at SiO2/SiC interface, dual-beam Time-of-flight Secondary ion mass spectrometry (TOF-SIMS) with low energy sputtering beam was available. In addition to the experimental profiles, simulation using MRI model, in which Mixing, Roughness and Information depth were employed as parameters, enabled to acquire a more authentic distribution at the SiO2/SiC interface. Slight discrepancy on depth profiles between samples with different surface roughness was duplicated on the convoluted profiles in the simulation. Moreover, reconstructed profile of nitrogen indicated a real distribution with less impact of mixing and roughness, although that may contain uncertainty due to incompletion in the simulation model or variation of the distribution owing to detection species in the experiment. From the result of carbon profiles of both experimental and convoluted profiles, the relative discrepancy on the carbon distribution between samples was clarified, which suggested the possibility that a carbon thin layer at the SiO2/SiC interface would be found in the future.

Investigation of the Pump, Dissipation and Inverse Turbine Operating Modes Using the CATHARE-3 One-Dimensional Rotodynamic Pump Model

A predictive transient one-dimensional rotodynamic pump model is currently developed into the CATHARE-3 thermal-hydraulic system code at CEA Saclay, France. Flow is computed in each part of the pump (suction, impeller, diffuser, volute and discharge pipe) based on the definition of a mean stream line. Several cells are used to mesh each part of the rotodynamic pump, which makes this model different from usually called “1D models”. In this study, the model is tested on a medium specific speed centrifugal pump in every operating modes encountered in the first quadrant (positive flow rate and rotational speed). A flow rate evolution is performed at the nominal rotational speed and also at rotational speed equal to zero in order to produce complete first quadrant homologous curves. Relative discrepancy between computation and experiment is respectively less than 10% and 15% on the whole obtained homologous head and torque curves.

Preliminary Numerical Estimation of Selected Terminal Ballistic Effects Produced by Explosion of Mortar Projectile

Results of theoretical modelling of mortar projectile’s fragments propulsion were shown. Taking into account universality of application of the considered ammunition, it seems to be reasonable to conduct simulations of projectile’s fragments propulsion and interaction with the environment. In the conducted investigations, due to dynamic character of the whole phenomena, characterized by extremely high values of strains and strain’s rate, the meshless explicit approach was used (Smoothed Particle Hydrodynamics method implemented in AUTODYN software). This approach minimalized the negative effects of deformation of “classical” Lagrangian mesh. In order to validate a numerical model, the results were compared with the simplified Gurney’s formula, which provides high accuracy of fragment’s velocity for regular shapes of casing. Comparison of the results showed low value of relative discrepancy (lower than 10%) for the cylindrical part of the casing in which detonation was fully developed and resulted in higher values of relative discrepancy of initial velocity for the non – cylindrical region, especially where the detonation was not developed.

A Comparison over Time of Relative Discrepancy Scores of Low Achievers

The accurate differentiation of learning disabled (LD) students from other low achieving students and the provision of effective remedial services continue to be important issues in the field of learning disabilities. Despite numerous criticisms, the calculation of a discrepancy between ability and achievement is used widely in the identification of students with learning disabilities. In the present investigation, the stability of discrepancies for LD and non-LD, low achieving students was examined. A differential change in relative descrepancy scores was found between the two groups of students from grades two to five. LD and non-LD groups did not differ significantly in second grade but did differ significantly in fifth grade in terms of relative discrepancy. Results and the implications for service delivery models are discussed.