Добірка наукової літератури з теми "Boolean material removal"

The simulation of computer numerically control (CNC) machining process is an important component of CAM, it can check errors and enhance the automation of machining process. In order to realize the material removal simulation of machining process through VC++ and OpenGL, this paper does the research on the Boolean operations based on the Constructive Solid Geometry (CSG) modeling technique. Firstly, this paper introduces the CSG technique, especially the creating complex object from simple primitives by the operations of Boolean algebra and the frame buffer. Then this paper achieves the solid modeling of cutter and stock through VC++ and OpenGL, and does the research on the theory of cutter’s swept volume generation. In terms of the theory, a cutter’s swept volume is created. Finally, the Boolean difference operation of a stock and the cutter’s swept volume is realized, and the code is also given.

Warehouse accumulates non-value added or wastes activities consist of inventory, waiting and transportation. The warehouse is a must to prevent any unforeseen events causing failures to implement the Just-In-Time concept. However, the existence of the warehouse will increase the operation expenditure and can lead to the profit losses. Therefore, the manufacturer needs to identify and eliminate the wastes to reduce the consumption of the resources and keep minimum requirement of the activities such as inventory, waiting and transportation in the warehouse. Value Stream Mapping is one of the Lean tools as an approach to eliminate the non-value added or wastes. This tool visualizes the information and material flow of the manufacturing activities. The development of a model based from Value Stream Mapping determined the current state of the wastes existed in the warehouse activities. The model is used to identify and eliminate the waste in the warehouse. From the information flow, the optimum combination of the wastes was determined through Boolean concept. The wastes are simplified and combined by passing through the Boolean operators consist of AND Gate and OR Gate. The expected outcome of this paper is to propose a conceptual model of new value stream mapping to identify and eliminate the waste in the warehouse. From the removal of wastes, the profit can be increased by reduction of the operation expenditure of the manufacturer.

5-axis flank milling is applied extensively in aerospace, die-molds, and automotive industries because of high efficient material removal rate. Commercial CAM software can only simulate the tool path and collision at present, but cannot handle with cutting force during cutting process due to the variable geometrical cutter workpiece engagement (CWE) region of 5-axis milling. This paper presents a novel solid analytical model for extracting the CWE maps. The CWE is obtained analytically by performing Boolean operations between the cutter and in-process-workpiece (IPW) at any given cutter location (CL) point, instead of using the cutter and the removal volume. The proposed process simulation method could identify the CWE efficiently and precisely for general cutting tools. Finally, the CWE boundaries are mapped from a 3D space into a 2D plane defined by the immersion angle and the axial depth of a given cutter. The proposed solution can be easily integrated into the CAM software for predicting milling force and optimizing parameters in 5-axis milling.

In this paper, B-rep solid modeling techniques are used to deal with geometric modeling issues encountered in ball-end milling simulation. The precise B-rep model of the cutter swept volume is developed using advanced sweeping/skinning techniques. Semi-finishing operations are simulated by performing consecutive Boolean operations between the updated part and swept volume. The instantaneous chip geometry is accurately and reliably extracted from the B-rep model of the updated part. Also, the material removal in ball-end milling is precisely simulated for finishing operations, in order to construct the feed-mark and scallop geometries. The validity of the final model is confirmed by comparing the predicted feed-mark profile with experimental measurements. The system developed can be used to verify and optimize NC codes, thus contributing to improving reliability, accuracy, and productivity in CNC machining.

Vascular-free flaps are the most frequently employed method in cases of jaws reconstruction after large tumor removal. This therapeutic choice is due to its intrinsic blood supply, which speeds up recovery and enables healing apart from the injured recipient site. This method is most commonly used in secondary reconstructions brought on by radiation, infection, or prior surgical intervention. In fact, with the help of 3d technology, guides can be designed to perform the grafting very smoothly. The purpose of this review with meta-analysis is to compare the two methods: the one using 3d and the freehand one. Methods: In accordance with the entered keywords, a literature search was conducted on PubMed, Lilacs, and Web of Science. Articles published between 2000 and 4 January 2023 were taken into consideration. Using the Boolean connective AND, the terms “jaw reconstruction”, “cad-cam”, and “cancer” have been joined. Results: After searching the three search motors, 148 articles were selected, and only 7 were chosen for this review. Conclusions: The pre-operative morphological position looks to be accurately restored using the CAD/CAM reconstructive methodology. Reconstruction using CAD-CAM and 3d technology allows for greater accuracy, less operative time, and improved aesthetics.

Esta pesquisa objetivou descrever o efeito de diferentes substâncias na remoção de resíduos das paredes da câmara pulpar após o término do tratamento endodôntico. A busca foi executada por uma única pesquisadora nas bases de dados PubMed/MEDLINE, Biblioteca Virtual de Saúde (BVS), Web of Science, CINAHL, EMBASE, Portal de Periódicos CAPES, Scientific Eletronic Library Online (SciELO), Cochrane Library e em livros relacionados a temática. Utilizou-se os descritores “root canal filling materials”, “epoxy resins”, “mineral trioxide aggregate”, “cal-mer cements”, e termos livres“pulp chamber cleaning”, “chamber cleaning”, “sealer removal” e “coronary chamber cleaning”, unidos por operadores booleanos. Foram considerados elegíveis estudos relacionados a temática pesquisada, sendo excluídos artigos fora da restrição temporal estipulada de 5 anos. As buscas foram realizadas no período de novembro de 2021 a janeiro de 2022, sendo encontrados 34 artigos elegíveis. Inicialmente, os estudos foram selecionados por título e resumos independentemente, sendo eliminados os artigos duplicados e aqueles que não se enquadrassem na temática da pesquisa. Ao final, 3 estudos compuseram a revisão integrativa. Para a análise detalhada, organização e apresentação dos achados, foi realizada a leitura exploratória de todo o material selecionado, com o registro das informações pertinentes extraídas em um quadro específico. Com esta revisão, observamos que um microbrush embebido em solventes como eucaliptol ou óleo de banana pode apresentar uma remoção mais promissora de cimento obturados das paredes da coroa dentária.

INTRODUCTION: RULA (rapid upper limb assessment) is a survey method developed for use in ergonomics investigations of workplaces where work-related upper limb disorders are reported. There are various researches available regarding the use of RULA in assessing work-related musculoskeletal disorders (WRMSDs). But till date, there is no compiled review available regarding the comprehensive research on the uses of RULA in various ergonomic assessment. OBJECTIVE: To compile the availability of article related to the uses of RULA in assessing WRMSDs among workers from various fields. MATERIALS AND METHODS: The articles related to RULA in ergonomic assessment were searched using the reputed academic databases, including PubMed, Medline, CINAHL, PsycINFO, and EBSCO from inception to July 22, 2019 using the five keywords, “ergonomics,” “musculoskeletal,” “workplace,” and “rapid upper limb assessment.” These keywords were combined using the Boolean operators “AND,” “OR,” and “NOT.” RESULTS: A total of 263 articles (n=263) were identified. After the removal of 161 duplicate articles, 102 articles were screened for the analysis. Among then, 21 articles were excluded and 81 full-text articles were assessed for eligibility. Again 68 articles were excluded due to not meeting the inclusion criteria and finally 13 articles were included in the qualitative comprehensive analysis. CONCLUSION: The wider application of RULA has been confirmed from this comprehensive review.

Aims and Objectives: To review and report on the literature covering the cumulative survival and success of Mini Dental Implants (MDIs) supporting complete removable over-dentures. Materials and Methods: An electronic keyword search was carried out using PubMed for Medline (National Library of Medicine, Washington, DC), Google-Scholar, and the Web of Science® interface by M.C. and S.R. The standard and network approaches were utilised according to O’Connor (1992). The initial search was carried out from the 1st of December 2015 to the 31st of March 2016, followed by a second and final search finalised in November 2020. The above -mentioned data bases were searched using combinations of the following key words: Mini dental implant*, Mini-dental implant*, “Narrow diameter dental implant*”, “small diameter dental implant*”. Boolean operators (‘Or’ and ‘AND’) were used to expand, exclude and join keywords. Results: 20 full text articles were analysed. The cumulative MDI survival rate ranged from 66-100% at 1-8.7 years. Success rates ranged from 78-100% Conclusions: MDI survival rates were found to be lower than those of regular sized implants supporting removable complete over-dentures however success rates of MDIs are high in the short term and offer a very good alternative to regular sized implants. Failures and complications were more prevalent in the maxilla than in the mandible

Background: A correct tridimensional implant placement requires a sufficient amount of bone to completely satisfy the prosthetic reconstruction. Several techniques can be used to recreate the bone quantity. Among them, titanium meshes have shown great potential in space maintenance and fewer complications in case of exposure. Recently, 3D CAD, CAM technology, and specifically SLM have been used to produce customized meshes in titanium alloy. The aim Purpose of this systematic review is to evaluate new customized meshes compared to traditional ones in terms of new volume of generated bone and the incidence of complications. Materials and Methods: A MEDLINE/PubMed literature search was performed to find relevant randomized controlled clinical trials published in English up to and including December 2022. The Cochrane Database of Systematic Reviews and SCOPUS were also searched. The main keywords used in the search were: titanium meshe(s), customized titanium meshe(s), combined with AND/OR as Boolean operators, and bone augmentation with/and/or titanium mesh. Results: The electronic search identified 1002 papers in total, and after duplicate removal, 500 articles were screened. After a manual screening of the title and abstract, 488 studies were excluded, and 12 articles' full text of 12 articles was analyzed. Further analysis was performed to make sure that the articles matched the inclusion/exclusion criteria of the present review. Six additional articles were excluded in this phase. No meta-analysis was performed due to the heterogeneity of the data. Conclusion: By using traditional or customized devices with the newly generated bone volume allowed the implant placement in all cases. Complications were mainly reported as exposure during the healing phase, but the conclusions of whether customized or conventional systems perform one better than the other are still inconclusive.

Le toilage appartient à la famille des procédés de finition – superfinition abrasives. Il permet d’obtenir des surfaces ayant une très bonne rugosité. En outre, il s’agit d’une très bonne alternative pour la production à grande échelle, car c’est un procédé très efficace et stable. Malheureusement, le toilage reste un procédé difficile à optimiser et nécessite de nombreux essais avant de trouver les conditions optimales. La modélisation numérique du procédé de toilage est donc une excellente alternative aux optimisations empiriques qui prennent beaucoup de temps. Ce travail propose des méthodes de modélisation pour prédire la rugosité générée par le procédé de toilage. Après une campagne expérimentale visant à comprendre l’effet des paramètres du toilage sur l’intégrité de surface (rugosité et contraintes résiduelles), l’objectif de la thèse était de construire un modèle capable de prédire les rugosités générées par le procédé de toilage. Un nouveau modèle 3D cinématique a été développé. Le modèle se base sur la description cinématique du procédé de toilage et l’utilisation d’une mesure de toile réelle. Il consiste à simuler le rayage multi passe d’une toile sur une surface. La trajectoire de rayage de la toile est déterminée par la cinématique de toilage et l’interaction entre la toile abrasive et la surface de pièce usinée est supposée parfaite (opérations booléennes). Une première comparaison des rugosités prédites par le modèle et des rugosités expérimentales permet d’identifier les pistes d’amélioration du modèle pour une prédiction de rugosité plus réaliste. Pour tenir compte de la flexibilité du système galet-toile, un traitement numérique des topographies de toile a été proposé. Ce traitement permet d’aligner les grains à la même hauteur. Deux méthodes d’alignement de grains ont été explorées et comparées. L’effet de ces deux méthodes d’alignement sur les résultats de prédiction de rugosité a été étudié. Ceci a été suivi par une étude de sensibilité du modèle vis-à-vis des vitesses cinématiques. Cette étude de sensibilité a permis de conduire à des simplifications du modèle. Ces simplifications permettent de réduire le temps de simulation de 12 heures à moins de 3 minutes. Ainsi, le modèle 2D (adaptation du modèle 3D) a été développé. L’idée du modèle consiste à négliger l’effet du mouvement d’oscillation et de facto de simuler des rayages monodirectionnels. L’effet des paramètres de toilage (taille de grains, force de toilage et dureté de galet) a été étudié. Ensuite, une discussion sur la sensibilité du modèle vis-à-vis des dispersions de toile et des propriétés mécaniques de la pièce a été abordé. Les résultats de simulation permettent d’observer les mêmes tendances expérimentales, par contre les rugosités prédites sont plus faibles que les rugosités expérimentales. Ces observations ouvrent vers des pistes d’amélioration du modèle, à travers l’amélioration de la compréhension et la modélisation de l’indentation entre la toile et la pièce durant le procédé de toilage. Enfin, ce travail de thèse traite de la caractérisation de la tenue en fatigue (expérimentalement) en flexion rotative des éprouvettes obtenues par tournage dur et par tournage dur + toilage
The belt finishing belongs to the family of abrasive finishing processes. It allows obtaining surfaces with a very good roughness. Moreover, it is a very good alternative for large-scale production, as it is a very efficient and stable process. Unfortunately, belt finishing remains a difficult process to optimize and requires many trials before finding the optimal conditions. Therefore, numerical modeling of the belt finishing process is an excellent alternative to time-consuming empirical optimizations. This work proposes modeling methods to predict the roughness generated by the belt finishing process. After an experimental campaign aimed at understanding the effect of belt finishing parameters on surface integrity (roughness and residual stresses), the objective of the thesis was to build a model capable of predicting the roughness generated by the belt finishing process. A new 3D kinematic model was developed. The model is based on the kinematic description of the belt finishing process and the use of a real abrasive belt measurement. It consists in simulating the multi-pass scratching of a belt on a surface. The scratching trajectory of the abrasive belt is determined by the kinematics of the process, and the interaction between the abrasive belt and the machined surface is assumed perfect (Boolean operations). A first comparison of the roughness predicted by the model and the experimental roughness allows us to identify ways to improve the model for a more realistic roughness prediction. In order to take into account the flexibility of the roller-abrasive belt, a numerical treatment of the abrasive belt topographies was proposed. This treatment allows aligning the grains at the same height. Two grain alignment methods were explored and compared. The effect of these two alignment methods on the roughness prediction results was studied. This was followed by a sensitivity study of the model with respect to kinematic velocities. This sensitivity study led to simplifications of the model. These simplifications allow reducing the simulation time from 12 hours to less than 3 minutes. Thus, the 2D model (adaptation of the 3D model) was developed. The idea of the model is to neglect the effect of the oscillation movement, then to simulate unidirectional scratching. The effect of belt finishing parameters (grain size, toiling force and pebble hardness) was studied. Then, a discussion of the sensitivity of the model with respect to the abrasive belt dispersions and the mechanical properties of the part was addressed. The simulation results show the same experimental trends, but the predicted roughness is lower than the experimental roughness. These observations open the way to improvement of the model, through the improvement of the understanding and the modeling of the indentation between the belt and the part during the process of belt finishing. Finally, this thesis deals with the characterization of the fatigue strength (experimentally) in rotational bending of specimens obtained by hard turning and hard turning + sheet metal forming

An analysis system for solid mechanics applications is described in which a new finite element method that can accommodate general polyhedral elements is exploited. The essence of the method is direct polynomial approximation of the shape functions on the physical element, without transformation to a canonical element. The main motive is elimination of the requirement that all elements be similar to a canonical element via the usual isoparametric mapping. It is this topological restriction that largely drives the design of mesh-generation algorithms, and ultimately leads to the considerable human effort required to perform complex analyses. An integrated analysis system is described in which the flexibility of the polyhedral element method is leveraged via a robust computational geometry processor. The role of the latter is to perform rapid Boolean intersection operations between hex meshes and surface representations of the body to be analyzed. A typical procedure is to create a space-filling structured hex mesh that contains the body, and then extract a polyhedral mesh of the body by intersecting the hex mesh and the body’s surface. The result is a mesh that is directly usable in the polyhedral finite element method. Some example applications are: 1) simulation on very complex geometries; 2) rapid geometry modification and re-analysis; and 3) analysis of material-removal process steps following deformation processing. This last class of problems is particularly challenging for the conventional FE methodology, because the element boundaries are, in general, not aligned with the cutting geometry following the deformation (e.g. forging) step.

Introdução: A diabetes mellitus do tipo II é uma doença metabólica sistêmica que afeta grande número de pessoas, tem seu início marcado pela resistência à insulina, que é o hormônio responsável pela introdução dos nutrientes provenientes da alimentação para a célula, o que pode desencadear vários problemas de saúde como infarto, alterações na visão, obesidade, dentre outros. Porém com a mudança nos hábitos diários e investindo na inserção do exercício físico pode haver subterfúgios para diminuir os níveis séricos de glicose no sangue. A prática de exercício tem papel importante na vida do diabético, pois somado a medicação, traz controle glicêmico e maior qualidade de vida para esse indivíduo. Objetivo: O objetivo desta revisão é verificar a eficiência da prática de exercícios físicos em pacientes diabéticos do tipo II. Material e métodos: Trata-se de uma revisão de literatura, tendo como critério de inclusão artigos publicados entre os anos 2011 e 2021, e como critério de exclusão artigos que abordavam apenas o diabetes do tipo I ou a diabetes gestacional. A busca foi realizada nas plataformas Cochrane, Redalyc e PubMed, fazendo uso do operador booleano “and” utilizando os descritores “Physiotherapy”, “Diabetes” e “Physical Exercise”, com isso foram selecionados nove artigos que abordavam a temática. Resultados: foi verificado que a prática de exercício físico para o paciente com diabetes mellitus II influencia positivamente no controle da resistência à insulina e auxilia a minimizar suas complicações, como problemas circulatórios e cardíacos, além de proporcionar controle glicêmico, aumento da força, potência muscular, aumento da massa magra que essa tem a capacidade de remover a glicose do sangue, gerando bem estar. Conclusão: ficou evidente que o exercício físico praticado regularmente proporciona impactos positivos na vida dos diabéticos do tipo II, trazendo inúmeros benefícios como citado anteriormente, os quais são essenciais para promover boa qualidade de vida para esses indivíduos. Sendo viável e de grande importância que os profissionais de saúde indiquem e orientem os pacientes, sobre os benefícios que a prática do exercício pode trazer para sua vida