Predictive Stator Flux and Load Angle Control of Synchronous Reluctance Motor Drives Operating in a Wide Speed Range

This paper presents a new simplified finitecontrol- set model predictive control strategy for synchronous reluctance motors operating in the entire speed range. It is a predictive control scheme that regulates the stator flux and the load angle of the synchronous reluctance motor, incorporating the ability to operate the drive in the field-weakening region and respecting the motor voltage and current limits as well as the load angle limitation needed to operate this type of motor in the maximum torque per voltage region. The proposed control strategy possesses some attractive features, such as no need for controller calibration, no weighting factors in the cost function, good robustness against parameter mismatch, and smaller computational cost compared to more traditional finite-control-set model predictive control algorithms. Simulation and experimental results obtained using a high-efficiency synchronous reluctance motor demonstrate the effectiveness of the proposed control scheme.info:eu-repo/semantics/publishedVersio

Composite pontics for orthodontic patients with extraction spaces.

Esthetic orthodontic appliances continue to appeal to more patients, which results in objections to extraction spaces that remain for several months during orthodontic therapy. This has led orthodontists to design temporary pontics that fill extraction sites and that can be reduced as the spaces close. This report describes a simple, efficient, and expeditious technique for making such pontics. © 2010 Quintessence Publishing Co, Inc

Skeletal and dental components of Class II correction with the bionator and removable headgear splint appliances

The purpose of this study was to differentiate the dentoalveolar and skeletal effects to better understand orthodontic treatment. We evaluated the treatment changes associated with the bionator and the removable headgear splint (RHS). Methods: The sample comprised 51 consecutively treated Class II patients from 1 office who had all been successfully treated with either a bionator (n = 17) or an RHS appliance (n = 17). Class II patients waiting to start treatment later served as controls (n = 17). A modified version of the Johnston pitchfork analysis was used to quantify the dentoalveolar and skeletal contributions to the anteroposterior correction at the levels of the molars and the incisors. Results: Both appliances significantly improved anteroposterior molar relationships (2.15 mm for the bionator, 2.27 mm for the RHS), primarily by dentoalveolar modifications (1.49 and 2.36 mm for the bionator and the RHS, respectively), with greater maxillary molar distalization in the RHS group. Overjet relationships also improved significantly compared with the controls (3.11 and 2.12 mm for the bionator and the RHS, respectively), due primarily to retroclination of the maxillary incisors (2.2 and 2.38 mm for the bionator and the RHS, respectively). The differences between overall corrections and dentoalveolar modifications for both molar and overjet relationships were explained by skeletal responses, with the bionator group showing significantly greater anterior mandibular displacement than the RHS group. Conclusions: The bionator and the RHS effectively corrected the molar relationships and overjets of Class II patients primarily by dentoalveolar changes. (Am J Orthod Dentofacial Orthop 2008; 134: 732-41

Optimizing the design of preactivated titanium T-loop springs with Loop software

ATMA (Ormco Corp, Glendora, Calif) T-loop spring (TTLS), preactivated with a gable bend distal to the loop, holds promise for producing controlled tipping of the canines and translation of the posterior segment. However, there is currently no consensus as to where the preactivated gable bend or the loop should be placed, what the height of the loop should be, or how the interbracket distance changes the moments produced. Using the Loop software program (dHal, Athens, Greece), we systematically modified a .017 x .025-in TTLS (10 x 6 mm) that was preactivated with a 45 degrees gable bend distal to the loop, and simulated the effects. As the gable bend was moved posteriorly, the moment increased at the posterior bracket more than it decreased at the anterior bracket. As the loop was brought closer to the anterior bracket, the posterior moment decreased at the same rate that it increased anteriorly. As the loop was increased in size, the moments increased both posteriorly and anteriorly. As the interbracket distance increased, the posterior moment decreased, and the anterior moment remained constant. We concluded that the size of the loop should be slightly increased, to 10 x 7 mm, and it should be placed 2 mm from the anterior bracket, with a preactivation bend of 45 degrees, 4 to 5 mm from the posterior bracket (after 4 mm of activation)

Avaliação cefalométrica do tratamento da Classe II, divisão 1, de Angle com os aparelhos extrabucal de Kloehn e fixo edgewise: influência do padrão facial

O presente estudo foi realizado com o propósito de avaliar respostas cefalométricas ao tratamento com aparelho extrabucal de Kloehn associado ao aparelho fixo edgewise convencional. Telerradiografias iniciais (T1) e finais (T2) de dois grupos de 30 pacientes tratados com estes aparelhos foram selecionadas e definidas pelo índice cefalométrico de Jarabak para determinação do padrão esquelético craniofacial. Os grupos foram denominados favorável (hipodivergente) e desfavorável (hiperdivergente). A idade média, no início do tratamento, foi de 11,03 anos e final de 14,72 com o tempo médio de tratamento de 3,6 anos para o grupo favorável. No grupo desfavorável a idade inicial foi de 11,51 anos e final de 15,17 anos com tempo médio de tratamento de 3,4 anos. Foi utilizado um sistema de análise de resposta de tratamento em coordenadas X e Y representativos dos movimentos dentários e das bases ósseas decompondo-os em seus vetores horizontais e verticais. Os resultados e respostas do tratamento foram analisados e comparados entre os grupos favorável e desfavorável utilizando o teste t-Student. Os resultados mostraram não haver diferenças estatisticamente significantes na resposta cefalométrica no tratamento com o aparelho extrabucal de Kloehn associados ao aparelho fixo edgewise quanto aos padrões faciais favorável e desfavorável. O tratamento promoveu uma restrição do deslocamento anterior maxilar e um menor deslocamento anterior mandibular. Quanto à movimentação dentária maxilar, houve uma restrição do movimento mesial e extrusivo dos molares superiores no grupo favorável, enquanto que o movimento dos dentes inferiores foi mínimo no sentido anterior e vertical.The aim of the present study was to evaluate the cephalometric response to Kloehn extraoral associated to fixed appliances treatment. Initial cephalometric radiographs (T1) and final ones (T2) of two groups composed by 30 patients were selected according to Jarabak index as favorable (hypodivergent) and unfavorable (hyperdivergent). The mean age on the beginning of the treatment was 11.03 years and the final mean age was 14.72, with a mean treatment time of 3.6 years for the favorable group. In the unfavorable group, the initial age was of 11.51 years, and the final age of 15.17, with a mean treatment time of 3.4 years. It was used a X and Y coordinated system to response analysis, representing the dental and skeletal bases movement. The results and treatment responses were analyzed and the favorable and unfavorable groups compared using the t-Student test. There were no statistically significant differences in the cephalometric response of Kloehn extraoral associated to fixed appliances treatment between the two groups. The treatment promoted a restriction of the anterior displacement of maxillary base and a lesser mandibular anterior displacement. Considering the upper teeth movement, there was restriction of the mesial and extrusive movement of the upper molars in the favorable group while the lower teeth movement was minimum on the anterior and vertical sense

Effects of stress relaxation in beta-titanium orthodontic loops

Introduction: This study evaluates the changes in the force system of the beta-titanium T-loop spring (TLS) caused by stress relaxation. Methods: Ninety TLSs with dimensions of 6 x 10 mm, made of 0.017 x 0.025 in beta-titanium alloy and preactivated by concentrated bends, were randomly distributed into 9 groups according to the time point of evaluation. Group 1 was tested immediately after spring preactivation and stress relief by trial activation. The other 8 groups were tested after 24, 48, and 72 hours, and 1, 2, 4, 8, and 12 weeks. By using a moment transducer coupled to a digital extensometer indicator adapted to a universal testing machine, the amounts of horizontal forces and moments and the moment-to-force ratios were recorded at every 0.5 mm of deactivation from 5 mm of the initial activation in an interbracket distance of 23 mm. Results: The horizontal forces and moments were higher (P < 0.001) for group 1 compared with the other 8 groups, which were not different among themselves. All groups produced similar moment-to-force ratios (P 5 0.600), with no influence of time. Conclusions: The TLSs preactivated by concentrated bends had progressive load decreases over time, and this effect is critical in the first 24 hours. (Am J Orthod Dentofacial Orthop 2011;140:e85-e92)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Force system evaluation of symmetrical beta-titanium T-loop springs preactivated by curvature and concentrated bends

Introduction: The objective of this research was to compare the effect of preactivation on the force system of beta-titanium T-loop springs (TLSs). Methods: Twenty TLSs with dimensions of 6 x 10 mm, of 0.017 x 0.025-in beta-titanium alloy, were randomly divided into 2 groups according to their preactivation. By using a moment transducer coupled to a digital extensometer indicator adapted to a testing machine, the amounts of horizontal force and moment produced were recorded at every 0.5 mm of deactivation from 5 mm of the initial activation in an interbracket distance of 23 mm. The moment-to-force ratio, the "neutral position" and the load-deflection ratio were also calculated. Results: TLSs preactivated by curvature delivered horizontal forces significantly lower than those preactivated by concentrated bends. No differences were found in relation to the moments produced throughout the deactivation of both groups. The moment-to-force ratios were systematically higher on the TLSs preactivated by curvature than those preactivated by concentrated bends, except on 5 mm of activation. Significant differences were found in the load-deflection rates and "neutral position." Conclusions: The TLSs preactivated by curvature delivered lower horizontal forces and higher moment-to-force and load-deflection ratios than did those preactivated by concentrated bends. (Am J Orthod Dentofacial Orthop 2011;140:e53-e58)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

In vitro lingual bracket evaluation of indirect bonding with plasma arc, LED and halogen light

Authors - Magno AFF, Martins RP, Vaz LG, Martins LP Objectives - Evaluate the shear bond strength (SBS) and the adhesive remnant index (ARI) of indirect bonded lingual brackets using xenon plasma arc light, light-emitting diode (LED) and conventional quartz-tungsten-halogen light. Material and Methods - Lingual brackets were bonded indirectly to 60 premolars divided to three groups according to the curing light used: Group 1, plasma arc for 6 s; Group 2, LED for 10 s; and Group 3, halogen light for 40 s. After bonding, the specimens were subjected to a shear force until debonding. The debonding pattern was assessed and classified according to the ARI scores. The mean shear bond strengths were accessed by anova followed by the Student-Newman-Keuls test for multiple comparisons. ARI scores were assessed using the chi-square test. Results - The three groups showed significant differences (p < 0.001), with the averages of group 1 < group 2 < group 3. Groups showed no differences regarding ARI scores. Conclusion - Bonding lingual brackets indirectly with plasma arc, during 60% of the time used for the LED, produced lower SBS than obtained with the latter. Using LED during 25% of the time of the halogen light produced lower SBS than obtained with the latter. These differences did not influence the debonding pattern and are clinically acceptable according to the literature. © 2010 John Wiley & Sons A/S

A discrepância de tamanho dentário, de Bolton, na oclusão normal e nos diferentes tipos de más oclusões, bem como sua relação com a forma de arco e o posicionamento dentário

Esta pesquisa teve como objetivo geral avaliar a discrepância de tamanho dentário, na oclusão normal e nos diferentes tipos de más oclusões e a sua relação com as medidas que determinam a forma de arco e o posicionamento dentário na região anterior. Para tanto, foram estudados 185 pares de modelos de gesso, divididos em 4 grupos: Grupo 1 (composto por 41 pares com Oclusão Normal, sendo 20 do gênero masculino e 21 do gênero feminino); Grupo 2 (composto por 44 pares com má oclusão de Classe I, divisão 1, sendo 22 do gênero masculino e 22 do gênero feminino); Grupo 3 (composto por 54 pares com má oclusão de Classe II, sendo 28 do gênero masculino e 26 do gênero feminino) e Grupo 4 (composto por 46 pares com Classe III, sendo 23 do gênero masculino e 23 do gênero feminino). Observou-se que não ocorreu dimorfismo sexual entre as discrepâncias de tamanho dentário e os diferentes tipos de oclusão dentária; as proporções estabelecidas por Bolton não se aplicaram ao grupo com Oclusão Normal; na Oclusão Normal, Classe I, Classe II e Classe III, houve um predomínio de excesso dentário total (RAZ12) no arco inferior; na Classe I houve uma igualdade na distribuição de excesso dentário anterior (RAZ6) nos arcos superior e inferior; na Oclusão Normal, Classe II e Classe III, ocorreu um predomínio de excesso dentário anterior (RAZ6) no arco inferior, em relação ao arco superior; os excessos dentários não contribuíram na ocorrência das más oclusões e as discrepâncias total e anterior (RAZ12 e RAZ6) não interferiram diretamente nas larguras e comprimentos dos arcos, bem como no posicionamento dos dentes anteriores.The general purpose of this study was to evaluate tooth size discrepancy in normal occlusion and in different malocclusion types and its relationship to measurements which determine arch form and anterior tooth positioning. One hundred and eighty five sets of casts of leucoderms were divided into four groups: Group 1 (consisted of 41 pairs of models with Normal Occlusion, 20 males and 21 females); Group 2 (consisted of 44 pairs of models with Class I malocclusion, 22 males and 22 females); Group 3 (consisted of 54 pairs of models with Class II, div. 1, malocclusion, 28 males and 26 females) and Group 4 (consisted of 46 pairs of models with Class III malocclusion, 23 males and 23 females). No sexual dimorphism was observed between tooth size discrepancies and different types of dental occlusion; the proportions stated by Bolton were not applied to the Normal Occlusion group; in Normal Occlusion, Class I, Class II and Class III there was an overall ratio excess in the lower arch; in Class I there was an equal anterior excess distribution in upper and lower arches; in Normal Occlusion, Class II and Class III there was a prevalent incidence of anterior ratio excess in lower arch; upper arch excess did not contribute to malocclusion occurrence and overall and anterior discrepancies did not interfere with arch width and length, as well as with anterior tooth positioning