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Copyright of China Petroleum Machinery is the property of China Petroleum Machinery Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study proposes a method to automatically generate numerical control (NC) programs from 3D computer-aided design (CAD) models in STL (Standard Triangulated Language) format. In STL format CAD of models, the three-dimensional shape is represented as a collection of triangular meshes. This format has the advantage of eliminating the need for concern about compatibility issues with data formats of 3D CAD models. On the other hand, there is a challenge in obtaining machining features that represent the characteristics of the three-dimensional shape for extracting the machining removal region. The previous study proposed a method to extract the machining region and obtain geometrical features such as boss or pocket shapes from only a 3D CAD model in STL format. However, that method was limited to product shapes represented only by independent boss shapes or pocket shapes. Those forms could be machined only by contour line machining, also called 2.5-axis machining. For general product shapes, it is necessary to recognize chamfers or filet shapes and free-form surfaces. Furthermore, the ideal machining process should be based on not only the desired shape, but also the extracted machining features to shorten the machining time as much as possible. Therefore, this study proposes a method to extract machining features such as chamfers, filets or free-form surfaces and to calculate the tool path necessary for machining. This study also proposed a method to extract pocket or slot machining features from multiple boss shapes for efficient machining. The machining experiments were conducted to validate the effectiveness of the proposed method. The results demonstrate that the tool path automatically generated using the proposed method from a 3D CAD model in STL format can be machined without any trouble and with the accuracy needed for practical use.

Background: The purpose of a fixed prosthodontic treatment may vary from the restoration of a single tooth to the complete rehabilitation of full occlusion. Finish line design is important in any tooth preparation, as finish line ensures the success of the future prosthesis. Finish line affects not only retention but also stability of fixed prosthesis. The finish line must be distinct, uniform, and smooth. Finish line is important during tooth preparation for acceptable marginal adaptation. The finish line must be easy to prepare, it must be easy to duplicate in impression, conservative, and provide sufficient strength to restore material. Finish line design helps in measuring the surface detail recording ability of an impression material. Various tooth preparation designs have distinct finish lines. Objectives: To evaluate the finish line of the die in a fixed prosthodontic laboratory. Materials and Methods: This laboratory based descriptive, cross-sectional, observational study has been conducted in the department of prosthodontics, BSMMU, with a sample size of 125 working casts die having different finish lines. The purpose of this study was to observe the finish line of the die of the working cast by using a dental magnifying loop. Data was collected on the basis of type, location, and quality of the finish line and recorded on a predesign data collection sheet. Collected data were analyzed by using the chi-square test. A P-value

Background. This study evaluated the influence of different tooth preparation techniques and zirconia materials on marginal adaptation. Methods. Forty-eight healthy human maxillary first premolars were divided into two primary groups based on preparation design: group A (chamfer) and group B (vertical). Within each main group, there were three subgroups, comprising eight teeth each, distinguished by the type of zirconia material employed (Zircad LT, MT, and Prime by Ivoclar Vivadent). All the samples were prepared by the same operator using a dental surveyor. Intraoral scanning was performed on the prepared teeth. SironaInLab CAD 20.0 software was used to design crowns, which were subsequently generated using a 5-axis milling machine. The crowns were cemented to their respective teeth with self-adhesive resin cement. Marginal gap measurements were taken in micrometers (μm) before and after cementation at 16 sites per sample using a digital microscope at×230 magnification. The collected data were evaluated using statistical analysis using the independent t-test, paired t-test, and ANOVA at an 0.05 significance level. Results. The vertical preparation group exhibited the smallest marginal gap, while the chamfer group displayed the largest. This disparity was statistically significant (P

Background/purpose: Recent advancements in dental technology has led clinicians to convert from traditional methods to digital workflows. The purpose of this study was to analyze the effect of various finish line designs and occlusal morphologies on the accuracy of digital impressions. Materials and methods: Six maxillary molar crown preparations were designed by using a digital sculpting software program. The samples differed in finish line design and occlusal surface morphology. Three different finish line designs (shoulder, chamfer, and shoulder with internal round angle) and two different occlusal morphologies (sharp and rounded) were used, giving six groups. Using three different intraoral scanners, each group was scanned and compared with a reference scan obtained from an industrial scanner. The accuracy of each scan was studied, and the data were statistically analyzed. Results: A total of 180 scans were acquired by utilizing three different intraoral scanners. The reference scan was compared with the scans from each group and overall differences (marginal, axial, and occlusal) were assessed. A crown preparation with a chamfer finish line showed the lowest marginal discrepancy of 13.2 ± 4.18 μm while preparation with a shoulder finish line reported the highest discrepancy of 34.8 ± 7.9 μm (P

A high-speed permanent magnet motor is the core driving component of a centrifugal air compressor. The power of the centrifugal air compressor is output by the motor. Its safety and reliability are embodied in the stability of the rotor structure, which greatly affects the stability and working efficiency of the centrifugal air compressor. Much research has focused on the material strength, structural characteristics, and fit clearance of a high-speed rotor, whereas few research articles have focused on the influence of interference fit of high-speed and ultra-high-speed permanent magnet motors, and there is also little research on the thermal failure caused by temperature in high-speed motors. In this paper, the influence of the interference fit and temperature of the high-speed permanent magnet motor is studied. Using finite element analysis conducted by Ansys to obtain simulation data, the influencing factors of the strength of the interference are analyzed comprehensively in the centrifugal compressor rotor system. The interference value and rotational speed range are determined via numerical calculation. Under the condition of minimum interference, when the calculated speed reaches 137,628.82 rpm, the structure of the rotor is loose and fails, which is a mechanical failure caused by the relative sliding of the magnet and the sheath. The calculated speed value differs from the simulation result by about 1.2%. The simulation results show that the maximum stress of the structure can be reduced from 1186.1 MPa to 308.42 MPa by adding chamfer to the end covers in interference fit structure. The effects of interference value, rotational speed, temperature, and sheath thickness on the structure are also analyzed. From the perspective of temperature on structural reliability, the failure temperature of the structure decreases when the interference value increases. The lowest failure temperature is 182.3 °C when the interference value is 70 μm. After that, the interference value increases and the failure temperature increases. The reason for this is the interaction between radial stress and contact stress. These results are caused by the interaction between interference fit and temperature, which should be paid attention to when the structure of a high-speed permanent magnet motor is designed. [ABSTRACT FROM AUTHOR]

Background.: This study evaluated the influence of different tooth preparation techniques and zirconia materials on marginal adaptation. Methods.: Forty-eight healthy human maxillary first premolars were divided into two primary groups based on preparation design: group A (chamfer) and group B (vertical). Within each main group, there were three subgroups, comprising eight teeth each, distinguished by the type of zirconia material employed (Zircad LT, MT, and Prime by Ivoclar Vivadent). All the samples were prepared by the same operator using a dental surveyor. Intraoral scanning was performed on the prepared teeth. SironaInLab CAD 20.0 software was used to design crowns, which were subsequently generated using a 5-axis milling machine. The crowns were cemented to their respective teeth with self-adhesive resin cement. Marginal gap measurements were taken in micrometers (μm) before and after cementation at 16 sites per sample using a digital microscope at×230 magnification. The collected data were evaluated using statistical analysis using the independent t-test, paired t-test, and ANOVA at an 0.05 significance level. Results.: The vertical preparation group exhibited the smallest marginal gap, while the chamfer group displayed the largest. This disparity was statistically significant (P <0.05)> Conclusion.: The vertical preparation design illustrated significantly better marginal adaptation than the chamfer preparation design. Comparisons between materials showed comparable marginal gaps. The mean values of the marginal gaps in all groups increased significantly after cementation. [ABSTRACT FROM AUTHOR]

Background: patient satisfaction is one of the main concerns during the construction full coverage restoration. success of the crown depends on many aspects such as color, anatomic form, no pain or gingival inflammation, restoration integrity and finally retention of the restoration. Aim: To assess the effect of margin design (feather edge versus deep chamfer) of Bruxzir zirconia ceramic crowns on patient's satisfaction. Methodology: A total of twenty patients (age range 19- 50 years old) with premolar teeth requiring full coverage restorations, were randomly allocated into two groups (n= 10) according to the margin design tested; Group DC (control): deep chamfer and Group FE (intervention): feather edge. All crowns were constructed from monolithic Bruxzir zirconia. After crowns cementation, patient satisfaction was assessed using a customized questionnaire after 6 months & 1-year using Likert scale. The obtained data were tested for normality and expressed as frequency and percentages. Further Statistical analysis was performed using Chi square test. Results: Patient satisfaction was higher in FE group compared to DC group regarding pain and gingival health questions, with statistically insignificant difference between both groups (p<.0.05) after 6 months and 1 year follow up. Conclusions: Margin geometry (feather edge of deep chamfer) of all ceramic Bruxzir crowns achieved high level of patient satisfaction without affecting the patient satisfaction along one year follow up period. [ABSTRACT FROM AUTHOR]

Recent advancements in dental technology has led clinicians to convert from traditional methods to digital workflows. The purpose of this study was to analyze the effect of various finish line designs and occlusal morphologies on the accuracy of digital impressions. Six maxillary molar crown preparations were designed by using a digital sculpting software program. The samples differed in finish line design and occlusal surface morphology. Three different finish line designs (shoulder, chamfer, and shoulder with internal round angle) and two different occlusal morphologies (sharp and rounded) were used, giving six groups. Using three different intraoral scanners, each group was scanned and compared with a reference scan obtained from an industrial scanner. The accuracy of each scan was studied, and the data were statistically analyzed. A total of 180 scans were acquired by utilizing three different intraoral scanners. The reference scan was compared with the scans from each group and overall differences (marginal, axial, and occlusal) were assessed. A crown preparation with a chamfer finish line showed the lowest marginal discrepancy of 13.2 ± 4.18 μm while preparation with a shoulder finish line reported the highest discrepancy of 34.8 ± 7.9 μm (P < 0.05). Also, the occlusal discrepancies of the samples with rounded and sharp occlusal morphologies were 12.55 ± 3.09 μm and 19.13 ± 2.3 μm, respectively (P < 0.05). It has been suggested that chamfer finish line design and rounded occlusal anatomy may produce more accurate digital impression for single crown restorations. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of finish line design (chamfer and feather‐edge) and ceramic type on the internal and marginal fits of fixed partial dentures on abutment teeth. Materials and methods: Two typodont mandibular casts, missing right first premolar tooth, received tooth preparation on canine and second premolar abutments (one cast with chamfer finish line and the other cast with feather‐edge finish line). The preparation segment of each typodont model was scanned, 3D printed in resin, and then invested and casted in metal to obtain two metal models. Polyvinyl siloxane impressions were made for the metal models and poured in type IV stone. The stone models (n = 40) were randomly assigned into four groups (n = 10): chamfer finish line with heat‐pressed zirconia reinforced lithium disilicate fixed partial denture (CL), chamfer finish line with monolithic zirconia fixed partial denture (CZ), feather‐edge finish line with heat‐pressed zirconia‐reinforced lithium disilicate fixed partial denture (FL), and feather‐edge finish line with monolithic zirconia fixed partial denture (FZ). After the fabrication of ceramic restoration, micro‐computed tomography was used to evaluate the internal and marginal fits of each fixed partial denture. Data were statistically analyzed with three‐way ANOVA (α = 0.05). Results: There were no significant interactions between preparation type, material type, and tooth type at any of the areas assessed. There was significant difference (p = 0.01) between CZ (59.15 ± 4.6 µm) and FZ (73.6 ± 17.1 µm) groups at the finish line area. Regarding the horizontal marginal discrepancy area, there were significant differences between CZ (62.65 ± 10.5 µm) and FZ (90.05 ± 5.6 µm) groups (p < 0.001), CL (77.45 ± 8.1 µm) and CZ (62.65 ± 10.5 µm) groups (p < 0.001), and FZ (90.05 ± 5.6 µm) and CL (77.45 ± 8.1 µm) groups (p < 0.001). At finish line area, there was a significant difference (p = 0.018) between feather‐edge with canine (72.75 ± 13.3 µm) and chamfer with canine (59.05 ± 5.8 µm); however, there was no significant difference (p = 0.774) between feather‐edge with premolar (69.45 ± 12 µm) and chamfer with premolar (65.1 ± 7.4 µm). Moreover, there was no significant difference (p = 0.886) between feather‐edge with canine and feather‐edge with premolar. Conclusions: The internal and marginal fits of the ceramic fixed partial dentures can be affected by the finish line design and ceramic type. The feather‐edge finish line had a negative impact on the marginal and internal fits of ceramic fixed partial dentures at certain measurement points. Regarding the effect of finish line design on abutment teeth, the difference in fit was only detected at the finish line area of the anterior abutment (canine) with the feather‐edge finish line. [ABSTRACT FROM AUTHOR]

This study discusses a new design which utilizes chamfers to further improve the thermal performance of inner-outer circulation impingement double-layer microchannel heat sinks by simulations and experiments manufactured with 3-Dimension printing. In contrast to former designed inner-outer circulation impingement double-layer microchannel heat sinks, inner-outer circulation impingement double-layer microchannel heat sinks with chamfer shows significant advantages in improving overall thermal performance in power electronic cooling. The results of simulation are in good agreement with those of experiment in five 3-Dimensional printing tests. It is demonstrated that the introduction of chamfers is effective in controlling the thermal gradient on substrate of heat sinks, and reducing the peak temperature on substrate of inner-outer circulation impingement double-layer microchannel heat sinks with chamfer as a result. The best performance is presented by a 0.2 mm chamfer located on the corner of the inner-outer circulation shaft in inner-outer circulation impingement double-layer microchannel heat sinks with chamfer. Experimental studies and numerical simulations both indicate that inner-outer circulation impingement double-layer microchannel heat sinks with a 2 mm chamfer significantly enhances heat transfer characteristics. In addition, the average Nusselt number for inner-outer circulation impingement double-layer microchannel heat sinks with a 2 mm chamfer is higher than that of other tests. Moreover, inner-outer circulation impingement double-layer microchannel heat sinks with a 2 mm chamfer performs better than other designs in terms of the overall heat transfer performance, which is significantly better than inner-outer circulation impingement double-layer microchannel heat sinks without chamfers. • The novel structure combined inner-outer circulating and chamfers is presented. • The shaft diameter of the chamfer can influence the overall thermal characteristics. • The shaft diameter of chamfers generates the change of thermal performance. • Shaft diameter equalling 0.3 mm indicates the best overall thermal characteristics. [ABSTRACT FROM AUTHOR]

A high-speed permanent magnet motor is the core driving component of a centrifugal air compressor. The power of the centrifugal air compressor is output by the motor. Its safety and reliability are embodied in the stability of the rotor structure, which greatly affects the stability and working efficiency of the centrifugal air compressor. Much research has focused on the material strength, structural characteristics, and fit clearance of a high-speed rotor, whereas few research articles have focused on the influence of interference fit of high-speed and ultra-high-speed permanent magnet motors, and there is also little research on the thermal failure caused by temperature in high-speed motors. In this paper, the influence of the interference fit and temperature of the high-speed permanent magnet motor is studied. Using finite element analysis conducted by Ansys to obtain simulation data, the influencing factors of the strength of the interference are analyzed comprehensively in the centrifugal compressor rotor system. The interference value and rotational speed range are determined via numerical calculation. Under the condition of minimum interference, when the calculated speed reaches 137,628.82 rpm, the structure of the rotor is loose and fails, which is a mechanical failure caused by the relative sliding of the magnet and the sheath. The calculated speed value differs from the simulation result by about 1.2%. The simulation results show that the maximum stress of the structure can be reduced from 1186.1 MPa to 308.42 MPa by adding chamfer to the end covers in interference fit structure. The effects of interference value, rotational speed, temperature, and sheath thickness on the structure are also analyzed. From the perspective of temperature on structural reliability, the failure temperature of the structure decreases when the interference value increases. The lowest failure temperature is 182.3 °C when the interference value is 70 μm. After that, the interference value increases and the failure temperature increases. The reason for this is the interaction between radial stress and contact stress. These results are caused by the interaction between interference fit and temperature, which should be paid attention to when the structure of a high-speed permanent magnet motor is designed.

Copyright of Journal of Art History / Sanat Tarihi Dergisi is the property of Ege University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We introduce a new chamfering paradigm, locally connecting pixels to produce path distances that approximate Euclidean space by building a small network (a replacement product) inside each pixel. These “ RE-grid graphs” maintain near-Euclidean polygonal distance contours even in noisy data sets, making them useful tools for approximation when exact numerical solutions are unobtainable or impractical. The RE-grid graph creates a modular global architecture with lower pixel-to-pixel valency and simplified topology at the cost of increased computational complexity due to its internal structure. We present an introduction to chamfering replacement products with a number of case study examples to demonstrate the potential of these graphs for path-finding in high frequency and low resolution image spaces which motivate further study. Possible future applications include morphology, watershed segmentation, halftoning, neural network design, anisotropic image processing, image skeletonization, dendritic shaping, and cellular automata. [ABSTRACT FROM AUTHOR]

A novel wideband circularly polarized (CP) magneto-electric (ME) dipole 1 × 2 antenna array for millimeter-wave applications is presented in this paper. The magneto-electric dipole of a single radiator is designed by combining a pair of loaded short-circuited metallic patches acting as electric dipole with a bowtie-shape aperture and a pair of vertical metallic posts functioned as a magnetic dipole. The pair of metallic patches is fed by the bowtie-shape aperture etched on the top surface of shorted-end substrate integrated waveguide (SIW). By chamfering and adding perturbation on each rectangular patch, the proposed ME dipole antenna realizes circular polarization radiation. Measured results show that the proposed single radiator has an impedance bandwidth of 27.1% (24.29 to 31.9GHz) for S11

AutoCAD, one of the most popular drawing programs, has enriched over time the facilities offered in making drawings in terms of how to use different graphics, symbols, accuracy, speed, interface, etc. One aspect that gives it an advantage over other drawing programs is the ability to use the AutoLisp language in creating user's functions that can be used as commands in AutoCAD. In this article, the authors present a function made in AutoLisp, which, for the parts drawn in Autocad, facilitates the automatic dimensioning of the chamfers, in the usual format, considering the scale of the respective drawing or detail. [ABSTRACT FROM AUTHOR]

AutoCAD, one of the most popular drawing programs, has enriched over time the facilities offered in making drawings in terms of how to use different graphics, symbols, accuracy, speed, interface, etc. One aspect that gives it an advantage over other drawing programs is the ability to use the AutoLisp language in creating user’s functions that can be used as commands in AutoCAD. In this article, the authors present a function made in AutoLisp, which, for the parts drawn in Autocad, facilitates the automatic dimensioning of the chamfers, in the usual format, considering the scale of the respective drawing or detail.

Man‐made objects commonly exhibit rounded edges and corners generated through their manufacturing processes. The variation of surface normals at these confined locations produces shading details that are visually essential to the realism of synthetic scenes. The more specular the surface, the finer and more prominent its highlights. However, most geometric modellers represent rounded edges and corners with dense polygonal meshes that are limited in terms of smoothness, while tremendously increasing scene complexity. This paper proposes a non‐invasive method (i.e. that does not modify the original geometry) for the modelling and rendering of smooth edges and corners from any input polygonal geometry defined with infinitely sharp edges. At the heart of our contribution is a geometric structure that automatically and accurately defines the geometry of edge and corner rounded areas, as well as the topological relationships at edges and vertices. This structure, called SREC‐RT, is integrated in a ray‐tracing‐based acceleration structure in order to determine the region of interest of each rounded edge and corner. It allows systematic rounding of all edges and vertices without increasing the 3D scene geometric complexity. While the underlying rounded geometry can be of any type, we propose a practical ray‐edge and ray‐corner intersection based on parametric surfaces. We analyse comparisons generated with existing methods. Our results present the advantages of our method, including extreme close‐up views of surfaces with a much higher quality for very little additional memory, and reasonable computation time overhead. [ABSTRACT FROM AUTHOR]

Objective: Research on evaluation of crowns made by the latest contemporary dental computer-aided design/computer-aided manufacturing (CAD/CAM) systems for their marginal adaptation is scarce. The purpose of this in vitro study was to evaluate the marginal integrity of crowns fabricated by the latest Chairside Economical Restorations of Esthetic Ceramic (CEREC) system using 2 different finish line preparation designs: chamfer and shoulder.Materials and Methods: Typodont teeth were divided equally into 2 groups, A and B. The teeth were prepared for full coverage crowns with a shoulder (group A) and chamfer (group B) finish line design. An experienced prosthodontist prepared all crown preparations. Evaluation of 6 sites per sample was completed by 2 calibrated, experienced prosthodontists using the modified US Public Health Services (USPHS) criteria. The descriptive statistics and Z-test were used to evaluate the results.Results: A total of 180 teeth were included in the study (90 teeth in each group). Only 2 crowns in group A and 1 crown in group B were clinically unacceptable. There was no statistical significance (p = 0.282) between the 2 groups regarding finish line design.Conclusions: The CEREC system provides clinically acceptable crowns and can safely be utilized in dental treatment. Therefore, CAD/CAM restorations could be considered as a safe treatment modality by dental professionals. [ABSTRACT FROM AUTHOR]

• Buccal chamfer does not improve retention of reattached incisors for lingual load. • Chamfers strengthen incisor reattachment not by increasing bond area. • Lingual chamfer may play a key role in retention for upper incisor reattachment. This study aimed to evaluate the effect of different chamfer preparations on the load capacity of reattached fractured incisors under lingual loading. Eighty #8 typodonts were randomly assigned to four groups (n = 20 each). They were sectioned to simulate crown fracture, and reattached with a self-etch adhesive and a resin composite. The preparation for each group was: (1) no chamfer; (2) buccal chamfer; (3) lingual chamfer; and (4) circumferential chamfer. Forty-eight human lower incisors were grouped and prepared similarly (n = 12 each). These teeth were tested for their load capacity under a lingual load on a universal testing machine. Finite element models were used to examine the stresses on the reattached surfaces to help interpret the experimental results. The buccal chamfer did not increase the load capacity when compared with the no-chamfer group. Lingual and circumferential chamfers respectively increased the fracture load by 36.9% and 32.3% in typodonts, and 78.5% and 33.3% in human incisors. The increase was statistically significant (p < 0.05). A higher fracture load tended to be accompanied by a larger area of deflected cohesive fracture. Finite element analysis showed that lingual and circumferential chamfers reduced the fracture-causing tensile stress at the lingual margin of the reattachment interface by approximately 70% and 60%, respectively, in human upper incisors. It was the joint design, and not the size of the bond area, that affected the load capacity of reattached incisors. Among the preparations considered, only those with a lingual chamfer could increase the load capacity of reattached incisors under a lingual load. [ABSTRACT FROM AUTHOR]

We introduce a new chamfering paradigm, locally connecting pixels to produce path distances that approximate Euclidean space by building a small network (a replacement product) inside each pixel. These “ $RE$ -grid graphs” maintain near-Euclidean polygonal distance contours even in noisy data sets, making them useful tools for approximation when exact numerical solutions are unobtainable or impractical. The $RE$ -grid graph creates a modular global architecture with lower pixel-to-pixel valency and simplified topology at the cost of increased computational complexity due to its internal structure. We present an introduction to chamfering replacement products with a number of case study examples to demonstrate the potential of these graphs for path-finding in high frequency and low resolution image spaces which motivate further study. Possible future applications include morphology, watershed segmentation, halftoning, neural network design, anisotropic image processing, image skeletonization, dendritic shaping, and cellular automata. [ABSTRACT FROM AUTHOR]

Die Glaskante stellt einen besonderen Bereich in der Glasscheibe dar. Der herstellungsbedingte Eingriff in das Material aus den Bearbeitungsschritten Zuschnitt und Schleifen verursacht Fehlstellen auf der Oberfläche, welche die Festigkeit des Glases mindern können. Untersuchungen zur Kantenfestigkeit haben gezeigt, dass ein überwiegender Anteil der Gläser im Bereich des Saums oder im Übergang zur Glaskantenoberfläche bricht. Durch eine gezielte Neuentwicklung von Polierscheiben für den Saumbereich sollen Fehlstellen auf der Saumoberfläche und im Übergangsbereich zur Glaskante abgemindert und somit die Kantenfestigkeit erhöht werden. Zudem können die optischen Eigenschaften des Saums verbessert werden, um eine hochtransparente Glaskante herzustellen. Im Rahmen eines Forschungsprojektes an der Technischen Universität Dresden werden die Auswirkungen von unterschiedlichen Saumpolierscheiben auf die Oberflächen von Floatgläsern untersucht. Mit mikroskopischen Analysen werden Fehlstellen charakterisiert und Bruchursachen lokalisiert. Auf Basis erster Ergebnisse der Oberflächenanalyse wird die Qualität der verwendeten Polierscheiben bewertet. Influence of the polishing wheels on the surface quality of glass edges. Glass edges appear to be a peculiar zone of the glass. The interference into the material during the cutting and grinding process causes defects and cracks at the edge surface. Those defects can reduce the strength of the whole glazing. Former studies show that a major part of the glass break has its fracture of origin on the surface of the chamfer or the transition from the chamfer into the edge surface. A special development of polishing wheels for the chamfer shall improve the chamfers quality and consequently increase the edge strength. In addition, the optical characteristics should be improved to reach a highly transparent glass edge. Within the scope of a research project at the Technische Universität Dresden, we examined the impact of various polishing wheels on the chamfer area of annealed glass. A microscopic analysis enables to detect and characterize typical defects of the finishing processes and locates the fracture of origin. First results of the microscopic analysis allow to value the polishing wheels. [ABSTRACT FROM AUTHOR]

In order to solve the problem that the chamfer size of spiral bevel gears cannot be precisely controlled, a method for chamfering the tooth top with a conical cutter was proposed. This method established the tooth crest equation, and derived the tool path equation based on this. According to the taper angle of the conical cutter and the length of the chamfer, the position of the tool tip point and the tool axis vector could be calculated through geometric transformation. From this, the machining path of the tool was determined to complete the chamfering of tooth top. Simulation results showed that under three different chamfer parameters, the chamfer shape error was not more than 0.05 mm, which improved the chamfer accuracy, and could flexibly control the chamfer size. [ABSTRACT FROM AUTHOR]

Glass edges result from cutting glass sheets and a further optional finishing. The mechanical interference into the brittle material glass causes flaws and cracks at the edge surface. Those defects have an influence on the strength of the whole glazing. Within the scope of a research project at the Institute of Building Construction from the Technische Universität Dresden, the grinding and polishing process is examined in terms of characteristic visible effects on the glass edge and the edge strength. Thereby a special focus of the research project is the impact of various polishing cup wheels for the chamfer surface of annealed glass. The article presents some basics about the processing steps of glass edges surfaces, introduces the considered grinding and polishing cup wheels and gives an overview of the performed experimental examinations. A microscopic analysis enables a characterisation of typical defects at the surfaces. Furthermore, four-point bending tests are performed to determine the bending tensile stresses at failure. The combination of both methods enables an analysis of the fracture-causing defect before destruction and a correlation between the optical surface quality and the bending tensile stresses. Additionally, the microscopy could be used to support the adjustment of a grinding machine and control reproducible edge qualities. The evaluation shows that a special development of polishing cup wheels for the chamfer can improve the surface quality and consequently increases the edge strength.

Background: The most used types of retention of implant-supported prostheses are screw-retained or cement-retained restorations. The advantages and disadvantages of both have been identified by various authors over the years. However, cement-retained implant crowns and fixed partial dentures are among the most used types of restorations in implant prostheses, due to their aesthetic and clinical advantages. When cemented prostheses are made on implants, the problem of cement residues is important and often associated with biological implant pathologies. The objective of this research was to establish to what extent the techniques to reduce excess cement really affect the volume of cement residues. Materials and Methods: This review was written following the PRISMA statement; a detailed search was carried out in three different electronic databases—PubMed, Scopus, and Cochrane Library. The inclusion criteria were prospective clinical studies, with at least 10 participants per group, and with at least 6 months of the follow-up period. Results: There have been many proposals for techniques supposed to reduce the amount of excess cement in the peri-implant sulcus and on the prosthetic components, but of these, which are exceptional in their in vitro capabilities, very few have been clinically validated, and this represents the real limitation and a great lack of knowledge regarding this topic. Three articles met the inclusion criteria, which were analyzed and compared, to obtain the information necessary for the purposes of the systematic review. Discussion: Extraoral cementation can reduce the excess cement, which, after a normal excess removal procedure, is, nevertheless, of such size that it does not affect the possibility of peri-implant pathologies developing. All these studies concluded that a small amount of cement residue is found in the gingival sulcus, and using eugenol-free oxide cements, the residues were only deposited on the metal surfaces, with a better peri-implant tissues health. Conclusion: Despite the limitations of this study, it was possible to carefully analyze these characteristics and obtain valuable suggestions for daily clinical practice. Resinous cements are considered, due to the free monomers present in them, toxic for the soft tissues. The provisional zinc-oxide cements, also eugenol-free, represent the ideal choice. The different grades of retentive forces provided by these cements do not seem to have clinical effects on the decementation of restorations.

Objective: The aim of this study was to evaluate marginal fit of yttrium tetragonal zirconia polycrystals (Y-TZP)' copings with different finish line designs fabricated with various digital scanners and milling systems. Methods: Three model plastic teeth were prepared with three finish line designs: Design-1, continuous chamfer; Design-2, chamfer with shallow depression; Design-3, chamfer with deep depression. The "master models" were replicated using elastomeric polyvinyl siloxane impression material and poured in type IV stone generating 90 dies, 30 dies for each design. Dies were scanned and copings were milled utilizing three digital scanners and computer-aided design/computer-aided manufacturing (CAD/CAM) systems: System-1, InEos Red Scan (Sirona Dental Systems, Germany), Vitablocks® Mark II (VITA, Germany) copings milled by Cerec® inLab (Sirona Dental Systems, Germany); System-2, Cerec® AC Connect with BlueCam (Sirona Dental Systems, Germany), Vitablocks® Mark II (VITA, Germany) copings milled by Cerec® inLab (Sirona Dental Systems, Germany); and System-3, NobleProcera™ Optical Scanner (NobleBiocare™), procera zirconia coping milled by a Noble Procera™ milling machine (NobleBiocare™). Copings were seated on their respective "master models" and secured with uniform force. Eight measurements per coping were performed at pre-established points, with a metallurgical microscope (Zeiss, Germany) connected to a high precision digital video-micrometer (Javelin JV6000, California, USA) at 200 × magnification. Results: The tested systems demonstrated marginal gaps ranging from 12.4 to 26.6 µ m. Results for marginal fit of milled copings fabricated using three systems with different finish line designs differed significantly (p < 0.05). Procera zirconia copings scanned and milled with NobleProcera™ exhibited significantly lower marginal gaps compared to other specimen groups. However, InEos Red Scan/Vitablocks® Mark II/Cerec® inLab showed maximum marginal gaps among the study specimens. Conclusions: CAD-CAM manufactured Y-TZP' copings exhibited marginal gaps ranging from 12.49 to 26.6 µ m. The CAD-CAM fabrication system was a significant factor influencing the marginal misfit of Y-TZP' copings. Margin design exhibited system dependent influence on the marginal misfit. Marginal misfit observed for all systems were within clinically acceptable parameters. [ABSTRACT FROM AUTHOR]

Copyright of Revista Odontología Vital is the property of Universidad Latina de Costa Rica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Owing to effective aeration and energy dissipation, a stepped spillway is commonly used in a roller-compacted concrete (RCC) dam. However, its complex air-water flow features are far from being fully understood. Roughness density, step and cavity shapes are essential parameters. Numerical simulations are carried out to investigate their effects on hydraulic properties. In combination with the realizable k-ε turbulence model, the two-phase Mixture Model is used. The results indicate higher air concentrations for the spillway with rounded steps than the ones with trapezoidal steps; the roughness density and cavity shape show no observable effects on the aeration performance with cavity blockages. The characteristic air-water velocity for the trapezoidal steps layout is larger than that for the rounded steps. However, neither layout is sensitive to the roughness density; the velocity results for trapezoidal cavity and rounded cavity cases are almost independent of the roughness density. The velocity for all cases exclusive of trapezoidal steps increase with an increase in roughness density. The min. and max. pressures on the trapezoidal steps are slightly larger than those on the rounded steps; they increase with an increasing roughness density. The cavity shape and roughness density do not evidently influence the extreme pressures. Compared with the conventional step layout, chamfering the step edges slightly enhance the energy dissipation; partially blocking the cavities do not lead to any substantial change. In addition, the energy loss is not clearly related to the roughness density and step edge/cavity shape. [ABSTRACT FROM AUTHOR]

Based on the analysis of known methods of separation of bar mix to length determined that the most effective method of forming an annular groove therein plastic tapered section, with a gradual deformation of the metal disc blades recess which is destroyed in the mix zone. In order to reduce the depth of the groove after its shaping proposed to produce in the same local area flexural bar. Based on experimental data obtained an empirical formula relating the dependence of bending rod axis angle on the depth of the annular groove. It is found that the greatest effect on the angle of local bending rod axis in the annular groove zone occurs when changing its depth from 0.5 to 3.0 mm. And this dependence is exponential in nature. Reducing the local axis of the workpiece bending angle for the specified range of the groove depth will be between 8.83º to 2.23º. A further increase in the depth of the annular groove is not practical, because the angle of bending the rod axis with reduced insignificantly. The dependence is valid for the separation process rods tapered disc blades with a local curvature of its axis is almost independent of the original diameter shared assortment. Therefore, the process can be carried out efficiently when the groove depth is not greater than 3.0 mm.

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract The ability to minimize vibrations in milling by the selection of cutting edge geometry and appropriate cutting conditions is an important asset in the optimization of the cutting process. This paper presents a measurement method and a signal processing technique to characterize and quantify the magnitude of the vibrations in an end milling application. Developed methods are then used to investigate the effects of various cutting edge geometries on vibrations in end milling. The experiments are carried out with five cutting edge geometries that are frequently used in machining industry for a wide range of milling applications. The results show that a modest protection chamfer combined with a relatively high rake angle has, for the most of cutting conditions, a reducing effect on vibration magnitudes. Furthermore, dynamics of a highly positive versus a highly negative cutting geometry is explored in time domain and its dependency on cutting conditions is presented. The results give concrete indications about the most optimal cutting edge geometry and cutting conditions in terms of dynamic behavior of the tool. [ABSTRACT FROM AUTHOR]

Friction welding is a joining process that utilizes the force of pressure and heat from the friction to melt the tip of the workpiece in order to be connected. The research has been conducted to measure the influence of the length of one side chamfer to the characteristic of the tensile strength of steel JIS45Cr friction welding joints. The research was conducted by experimental method with rotation speed 1800 rpm, time kept at 50 seconds, load used was 3.5 kg, chamfer angle was 30º and the length chamfer were 3 mm, 5 mm, 7 mm, 9 mm and 11 mm. The tensile test conducted to find the effect of the chamfer length. The result of the research concluded that the highest tensile test on length variant of 7 mm, it was 97.3505 kN/mm2 and the lowest on 3 mm was 92.9868 kN/mm2. It is proved that the chamfer length effect to the tensile strength of friction welding.

Background and Aim: One of the problems of all ceramic restorations is their risk of fracture due to occlusal loads. The aim of the present study was to compare the effect of two marginal designs (shoulder and chamfer) on the fracture resistance of IPS-emax all ceramic restorations. Materials and Methods: One extracted maxillary first premolar received chamfer 50' marginal preparation (0.8 mm). Twenty impressions were made using poly vinyl siloxane. Then, chamfer was converted to shoulder 90'(1mm). After impression, epoxy resin dies were fabricated. Impressions of each epoxy resin die were made and poured with die stone. Twenty Press crowns and twenty ZirCAD crowns were made on stone dies and ce-mented on resin dies. Then, samples underwent a fracture test in a universal testing ma-chine. Data were analyzed by one-way ANOVA. Results: The mean fracture resistance was 1426N for the chamfer ZirCAD samples, 1361.3N for the shoulder ZirCAD samples, 1059.9N for the chamfer Press samples and 1295.8N for the shoulder Press samples. One-way ANOVA revealed no difference among groups. (p=0.095). Conclusion: After porcelain application, marginal design does not affect fracture resis-tance of single IPS-emax posterior crowns. Fracture resistance was approximately the same in Press and ZirPress groups probably due to porcelain application, because in Zir-CAD group fractures occurred in the porcelain prior to the core

In order to solve the problems of M-pressure pump crankshaft fracture,full analysis of the M-pump caranshaft fracture was congducted. On this basis,stress analysis was carried out on the crankshaft by ANSYS. Through simulation analysis found that severe stress concentration sites coincide with the cleavage site,and conducted a simulation influence on the fracture of the crankshaft chamfer,and re-determine the size of the chamfer. To further verify the situation fracture,the fatigue strenth of frature section were checking calculation by analtical method. The results show,fatigue strength safety factor below allowable safety factor under the original conditions of the crankshaft 4mm chamfer,and fatigue strength safety factor to meet the design requirements in the case of 8mm chamfer. Improved design was performed according to the results of the simulation and calculation of the crankshaft,and applications significant effect,solved the problem of crankshaft fracture.

Objectives: The objectives of this study were to evaluate the bond strengths of different adhesive materials, different tooth preparation designs and adhesive tooth preparation combinations to reattach fractured incisor fragments. Materials and Methods: The study sample comprised 48 intact human maxillary central incisors divided into two groups A and B. The incisal third was sectioned with a diamond disc. The teeth in Group A were reattached with bonding agent and in Group B with resin luting cement. The teeth in each Group were further divided into three sub-groups based on the preparation designs viz., simple attachment, chamfer on labial surface, groove with shoulder on labial surface and restored with nano-composite. Shear Bond Strength was calculated by applying load incisal to the fracture line. T-test and one-way ANOVA were used to evaluate the bond strength between the groups and within the group respectively. Results: Reattachment with resin luting cement showed high bond strength compared to bonding agent (P < 0.05). Within the subgroups ′groove with shoulder′ showed better bond strength compared to simple attachment and chamfer and the result was statistically significant (P < 0.05).Conclusion: Reattachment of fractured fragments can be considered as a good alternative treatment option when the fragment is available.Reattachment with resin luting cement and the preparation design of "groove with shoulder" showed better results.

Highlights • The behavior of cantilever beams, strengthened with CFRP is studied. • The effect of strengthening/anchorage method is evaluated. • Application of the anchorage efficiency of U-Wrap sheets with large chamfers enhanced the overall strength. Abstract The potential of improving the structural performance of concrete cantilever beams by extending the attachment of CFRP sheets to concrete columns through chamfers and fillets, constructed at beam-column connection, was investigated; while considering the impact of end anchorage using U-wraps of CFRP sheets or steel plates. Fourteen beam-column connections with 750-mm-long cantilever beams (150 × 150 mm) were load-tested after the attachment of CFRP sheets along the negative moment zone of the cantilever beams only or extending attachment of CFRP sheets' to the columns surface through creating chamfers and fillets at the beam-column joints. CFRP sheets' bond length and width, and number of layers, as well as the use of concrete chamfers and fillets had a significant impact upon mechanical performance of tested cantilever beams. End anchorage using U-wrap CFRP sheets was beneficial in delaying CFRP sheets debonding hence improving mechanical response; especially for cantilever beams, repaired by extending CFRP sheets to columns surface using large concrete chamfers. [ABSTRACT FROM AUTHOR]