Effects of Implanting Torques on Implant Osseointegration in an Animal Model

Objective: To investigate the effect of insertion torque on implant osseointegration in an animal model. Methods: First, the first to fourth premolars of nine healthy adult beagles’ mandibular were extracted to form an edentulous area, and then the beagles were equally divided into three groups with different torques (low torque: 10–30 Ncm; medium torque: 30–50 Ncm; high torque: > 70 Ncm). Three implants were placed on each side of the edentulous area of the beagles (54 total), and the dogs were observed for 8 weeks. Implant performance and removal torque values (RTV) were determined at 1, 4, and 8 weeks after surgery. In addition, the expression ratios of OPG and RANKL mRNAs in the surrounding bone tissue were determined. Results: None of the 54 implants showed loosening or loss, and no significant bone resorption was observed. The removing torques and the expression ratios of OPG and RANKL mRNAs showed differences at 1 and 4 weeks after surgery, while they converged at 8 weeks after the surgery (p > 0.05). Conclusion: The osteointegration process lasted approximately 8 weeks depending on the difference in parameters, and all parameters showed the same values even though the insertion torques at the beginning were different.

Effects of insertion torque values on the marginal bone loss of dental implants installed in sheep mandibles

The aim of the present in vivo study was to analyze and compare the effects on the crestal bone healing of two different implant macrogeometries installed in fresh socket areas and in normal bone areas with different insertion torque values. Two implant macrogeometries were used in the present study, DuoCone implant (DC) and Maestro implant (MAE), forming four groups: group DCws, in which the implants were installed in healing bone (without a socket); group DCfs, in which the implants were installed in post-extraction areas (fresh sockets); group MAEws, in which the implants were installed in healing bone (without a socket); group MAEfs, in which the implants were installed in post-extraction areas (fresh sockets). After 30 and 90 days of implantations in the bilateral mandibles of 10 sheep, eighty implants were evaluated through digital X-ray images and histologic slices. The crestal bone position in relation to the implant platform shoulder was measured and compared. The measured insertion torque was 47.2 ± 4.69 Ncm for the DCws group, 43.4 ± 4.87 Ncm for the DCfs group, 29.3 ± 3.16 Ncm for the MAEws group, and 27.7 ± 4.41 Ncm for the MAEfs group. The radiographic mesio-distal and histological bucco-lingual analyses showed significantly greater vertical bone loss in the implants installed with high torque (DC groups) in comparison to the implants installed with a low torque (MAE groups) (p < 0.05), at both evaluation times. In general, low insertion torque values (Maestro implants) showed better results of MBL when compared to implants installed with higher torque values (Duo Cone implants). Moreover, our results showed that the implants installed in the sites without sockets showed a less MBL in comparison with the implants installed in sites of fresh sockets.

Extending DC Bus Utilization for Induction Motors with Stator Flux Oriented Direct Torque Control

This paper presents a method to extend the DC bus utilization on an induction motor (IM) by using a combination of Space-Vector Modulated Direct Torque Control (DTC–SVM) and conventional DTC. The scheme proposed in this paper exploits the advantages of both control methods. During the linear region, it allows for a low torque ripple and low current harmonic distortion (THD). During the overmodulation region, it allows for the fastest torque response up to the six-step operation region. In both regions, there is complete independence of the motor parameters. The paper describes a way to provide a smooth transition between the two control schemes. Non-linearities affect the stator flux angle estimation, which leads to the inability to decouple torque and flux. To overcome this problem, a novel PI-based control scheme as well as a simplification on the decoupling terms’ calculation are proposed. Simulation and experimental results are presented to verify the feasibility of the proposed method.

On the Optimal Selection of Flux Barrier Reconfiguration for a Five-Phase Permanent Magnet Assisted Synchronous Reluctance Machine for Low-Torque Ripple Application

This paper aims to investigate the reconfigurations of rotor flux barriers for a five-phase Permanent Magnet Assisted Synchronous Reluctance Machine (PMASynRM). To precisely study the performance of the proposed configurations, a conventional PMASynRM with double-layer flux barriers is included in the study. Since the novel rotor schemes consume the same amount of rare-earth magnets, steel sheet materials, and copper wire, resulting in no extra manufacturing costs, the optimal reconfiguration should be determined, providing developed electromagnetic characteristics. Thus, all the proposed models are designed and analyzed under the same condition. The Lumped Parameter Model (LPM) is exported to the Finite Element Method (FEM) for precise analysis to reach developed torque and lower values of torque ripple. Based on the FEM results the model presenting the lowest torque fluctuations is selected as the optimal model and dynamically investigated. According to the results, in comparison with the conventional model, the introduced rotor designs provide a much lower value of torque fluctuations with a desirable amount of electromagnetic torque and power. In addition, the optimal model presents high values of power factor and efficiency, making it a vital alternative for low-torque ripple high-speed operations with no extra cost to the implementation process.

Use of Obturating Pills Combined with Low Concentration Acid Pills to Overcome Differential Stuck Challenges in Highly Deviated Wells

In 2020, A Major Offshore Operating Company in UAE faced a high differential pressure stuck event. This took place, during the execution of formation evaluation with a conveyed pipe sampling BHA. It is well known that after a differentially stuck pipe event happens, the success ratio will be time dependent (i.e. the less time a pipe remains stuck, the more chances there will be for it to become released) and the chances of releasing the BHA are always limited to the logging tools tensile limitations. One of the most common and successful methods to release differentially stuck BHA's specifically in limestone formations is by pumping and soaking acid pills. However, under such a high differential pressure environment, the use of acid may induce losses in the so called "thief zones", causing worse problems. The standard release procedure started by working the string within the tensile limits, followed by pumping acid pills (using the available volume mobilized before spudding each drilling section). During the first acid pills pumped to attempt to release the stuck pipe, loss volume pump rates, acid pill position(s) and coverage in the annulus was assessed and evaluated. Based on the results it was observed that the thief zone was in direct contact with the Pipe Conveyed circulation port, at the latching assembly. This then created a situation whereby, the acid pills were lost immediately after the acid came into contact with the formation. Utilizing low acid concentration pills also had the same effect. The solution was to pump an Obturating pill made-up of a weighting agent as a spacer behind the high volume, low concentration acid pill with crosslinking divergent chemicals, pumped at a high flow rate. This solution reduced the acid losses across the thief zone and once the Obturating pill came into contact with the loss zone, it facilitated the seal and cured the losses, by allowing the acid to move up the annulus until it reached the differentially stuck point and soaked across the problematic area. Once the acid pill was successfully placed at the required location using this method, the string was worked and successfully released. This combination of low concentration acid along with crosslinking divergent chemicals coupled with the Obturating pill behind the acid helped a major offshore operating company to pump the acid pill under partial losses only, to regain full circulation after only 10 bbl. of Obturating pill had entered inside the annulus. It allowed the acid pill to react across the stuck point, while keeping the string under low torque and compression. The operator was able to release the sampling BHA and bring it back to surface avoiding a lost in hole cost of around 4 MM$. The Obturating pill combined with low concentration CDC acid pill is proven to be a successful method in drilling operations when trying to release differentially stuck BHA's within a wellbore.

A mathematical model of a brushed DC motor system

Mathematical model has been proposed for some system that involves a brushed DC motor and it is widely used in industry. Brushed DC motor ideals for applications with a low- torque, manage to change pace or speed and it is widely used in many applications such as x-y table positioning system, conveyor systems and other system that required to use the features that brushed DC motor have. Mathematical model of brushed DC motor in order to verify the performance of the DC motor. In this paper, mathematical model of brushed DC motor will be derived from a brushed DC motor circuit that consist of two parts that are electrical and mechanical part. To validate the functionality of mathematical model, the performance of the brushed DC motor without any controller will be compared with the brushed DC motor with the presence of PI-PD controller that will be tuned by trial-and-error method. Performances of both brushed DC motor with and without controller will be compared in terms of transient response which are, rise time, Tr, settling time, Ts, steady state error, ess and lastly percentage overshoot. At the end of the study, the brushed DC motor with PI-PD controller show a better performance compared to the brushed DC motor without any controller.

Comparative Evaluation of Control Techniques of PMSM Drive in Automotive Application

This paper deal with comparative evaluation of control techniques of Permanent magnet synchronous motor (PMSM) drive in automotive application is investigated. The FOC, DTC and proposed SVM-DTC with LC-Snubber circuit are presented. In SVM-DTC, this reduces low torque ripple by using space vector modulated. The parameters of FOC, DTC and proposed SVM-DTC with LC-Snubber method are studied by simulation. The simulation analysis of control method is investigated in terms of speed, current and torque ripples It was observed that the proposed method upgrade the performance of PMSM drive in respect to speed, current ripples, and torque responses

Experimental Validation of Subsystem Models for a Novel Variable Displacement Hydraulic Motor

A novel, variable displacement, low-speed high-torque hydraulic motor is being developed that is expected to be highly efficient across a broad operating range. To ensure the final hardware achieves the expected performance, the models used in the development of the motor must be experimentally validated and revised. The focus of this work is on mechanical energy loss models that were used to guide the design of a single-cylinder motor prototype and then experimental tests used for validation. Losses were modeled and organized into five primary groups: main shaft bearings, main shaft seal, case windage, valve actuation, and linkage losses. The single-cylinder prototype was fabricated, and test parameters were defined. Two test rigs were designed and built to capture losses of the motor experimentally; one was used to collect low torque, zero/low-pressure differential results, and the other used to collect high torque, high-pressure differential results. A staged assembly procedure was developed to capture the independent contributions of each loss. By reviewing the quality of correlation between test observations and model predictions and revising the model when necessary, the models were validated. The correlation was improved by reviewing and modifying model inputs. This allows future solutions to be more accurately predicted in the design phase to drive the design of better machines. The validated model package was able to predict the motor performance within an acceptable range of error.

Tratamento ortodôntico interceptativo utilizando aparelhos autoligáveis passivos com prescrições individualizadas – fase 1: relato de caso

INTRODUÇÃO: A dentição mista é um dos estágios do desenvolvimento da oclusão no qual ocorrem muitas transformações, não só em relação às trocas dentárias, mas também no crescimento e desenvolvimento facial. Nesse momento, podem surgir diversos tipos de manifestações de má oclusão, sendo uma excelente época para se interceptar problemas que podem interferir no correto crescimento e desenvolvimento do complexo dentomaxilar. Entre os diversos tipos de tratamentos interceptativos, o uso de aparelhos fixos autoligáveis passivos com prescrições individualizadas é uma excelente opção para efetuar o alinhamento e nivelamento de forma parcial em alguns dentes. Em casos selecionados, essa mecânica pode reduzir a indicação de extrações seriadas ou expansão rápida de maxila. A sua indicação é mais precisa para os casos nos quais existem apinhamentos com dentes de tamanho normal, na presença de atresia das arcadas com compensação vestibulolingual. OBJETIVO: O presente artigo mostra um caso clínico que utilizou, como opção de tratamento interceptativo na dentição mista, braquetes autoligáveis passivos e torques individualizados para corrigir um apinhamento severo nos incisivos inferiores, obtendo espaço para os incisivos laterais com necessidade de expansão transversal das arcadas dentárias. RESULTADOS: Em dois anos de tratamento, os incisivos alinharam-se, com um suave aumento da sua inclinação. Na avaliação de três anos pós-tratamento, com os pré-molares, caninos e segundos molares permanentes já irrompidos, o ganho de espaço e a posição dos incisivos permaneceram estáveis mesmo sem contenção. O efeito ortodôntico mais significativo foi a correção do apinhamento severo na arcada inferior utilizando-se prescrição de baixo torque (LOW torque). Ocorreu um controle da inclinação para vestibular, com IMPA inicial de 95o para 100o e, após três anos, IMPA = 102o . Na arcada superior, não houve grandes movimentações dos incisivos para vestibular, com 1.PP inicial de 112o para 115o , sem modificação após três anos. O tratamento interceptativo corrigiu os problemas de alinhamento dentário, com a normalização dos trespasses horizontal e vertical dos incisivos, proporcionando uma condição favorável para o desenvolvimento mandibular natural, com a redução da discrepância sagital entre maxila e mandíbula (ANB: inicial = 8,0o , final = 6,0o , controle após 3 anos = 3o ). CONCLUSÃO: Essa estratégia de tratamento interceptativo foi eficiente na correção do apinhamento severo dos incisivos inferiores na dentição mista, com controle da inclinação desses dentes e com resultados estáveis após três anos sem contenção.