scholarly journals Measurement of Long-Term Dimensional Stability of Glass Ceramics Using a High-Precision Line Scale Calibration System

2011 ◽  
Vol 5 (2) ◽  
pp. 120-125 ◽  
Author(s):  
Akira Takahashi ◽  
Keyword(s):  
Dimensional Stability ◽  
Laser Interferometer ◽  
Glass Ceramics ◽  
Length Measurement ◽  
Secular Change ◽  
Calibration System ◽  
Synthetic Quartz ◽  
Line Scale ◽  
Scale Calibration

Length measurement was conducted for two years on glass ceramics, Zerodur®and Clearceram®, which have a low coefficient of thermal expansion, and on synthetic quartz. Commercially available glass ceramics were used for evaluating long-term stability, or secular change. Synthetic quartz ensured longterm length measurement stability. Two line scales of 300 mm length made of each material for a total of six line scales were simultaneously manufactured and measured to evaluate dimensional stability variation of the materials over time. Measurements were conducted with a line scale calibration systemdeveloped by Nikon. The calibration system is a onedimensional laser interferometer, featuring reduced Abbe’s errors, laser interferometer paths in a vacuum and real-time wavelength calibration of laser frequency using a 633 nm iodine-stabilized He-Ne laser. Long-term quartz stability was 4.3 nm and 5.4 nm (2σ). The yearly stability coefficients of the two glassceramic scales were -0.22 and -0.23 parts per million per year (ppm/yr) for Zerodur and -0.16 and -0.16 ppm/yr for Clearceram. No significant difference in stability between the two scales was observed for Zerodur or Clearceram.

Research of Dynamics of the Precision Mechatronical Line Scale Gage Calibration System

2015 ◽  
Vol 220-221 ◽  
pp. 550-553 ◽  
Author(s):  
Artūras Kilikevičius
Keyword(s):  
Mechanical System ◽  
Dynamic Properties ◽  
Length Measurement ◽  
Calibration System ◽  
Line Scale

In the paper, the research on the influence of drive fixing place on dynamic properties of the precision mechatronical line scales gage calibration comparator is analyzed. With the aim to research the influence of the drive on the mechanical system of the length measurement comparator, the drive mounting position was replaced, and the friction drive was changed for the rope drive.

High Bond Durability of Universal Adhesives on Glass Ceramics Facilitated by Silane Pretreatment

2018 ◽  
Vol 43 (6) ◽  
pp. 602-612 ◽  
Author(s):  
C Yao ◽  
H Yang ◽  
J Yu ◽  
L Zhang ◽  
Y Zhu ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Glass Ceramics ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Single Bond ◽  
Thermal Cycles ◽  
Universal Adhesive ◽  
Universal Adhesives ◽  
Resin Bonding

SUMMARY Objective: This study aimed to investigate the long-term effectiveness of ceramic–resin bonding with universal adhesives in non–silane-pretreated and silane-pretreated modes after 10,000 cycles of thermal aging. Methods and Materials: All Bond Universal, Adhese Universal, Clearfil Universal Bond, and Single Bond Universal were selected. Etched lithium disilicate glass ceramics were prepared, randomly assigned to groups, and pretreated with or without ceramic primer containing silane coupling agent prior to the application of universal adhesive (ie, silane-pretreated or non–silane-pretreated mode). The shear bond strength (SBS), microleakage, and field-emission scanning electron microscopy images of the ceramic–resin interfaces were examined after 24 hours of water storage or 10,000 thermal cycles. Light microscopy and confocal laser scanning microscopy (CLSM) were performed to analyze marginal sealing ability. Results: SBS and microleakage percentage were significantly affected by bonding procedure (non–silane-pretreated or silane-pretreated mode) and aging (24 hours or 10,000 thermal cycles). After the universal adhesives in the non–silane-pretreated mode were aged, SBS significantly decreased and microleakage percentage increased. By contrast, the SBS of Adhese Universal, Clearfil Universal Bond, and Single Bond Universal decreased, and the microleakage percentage of all of the adhesives increased in the silane-pretreated mode. However, after aging, the SBS of the silane-pretreated groups were higher and their microleakage percentages lower than those of the non–pretreated groups. In the non–silane-pretreated mode, adhesive failure was dominant and gaps between composite resin and the adhesive layer were significant when observed with CLSM. Conclusions: The simplified procedure reduced the ceramic–resin bonding effectiveness of universal adhesives after aging, and additional silane pretreatment helped improve the long-term durability.

Dynamic Mode of Line Scale Calibration

2006 ◽  
Vol 113 ◽  
pp. 447-452 ◽  
Author(s):  
Saulius Kaušinis ◽  
Aurimas Jakštas ◽  
Rimantas Barauskas ◽  
Albinas Kasparaitis
Keyword(s):  
Dynamic Mode ◽  
Line Scale ◽  
Scale Calibration

scholarly journals Observed Auroral Ovals Secular Variation Inferred from Auroral Boundary Data

Geosciences ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 351
Author(s):  
Bruno Zossi ◽  
Hagay Amit ◽  
Mariano Fagre ◽  
Ana G. Elias
Keyword(s):  
High Frequency ◽  
Field Model ◽  
Geomagnetic Latitude ◽  
Auroral Zone ◽  
Secular Change ◽  
Polar Cap ◽  
High Frequency Signal ◽  
Area Increase ◽  
Northern And Southern Hemispheres

We analyze the auroral boundary corrected geomagnetic latitude provided by the Auroral Boundary Index (ABI) database to estimate long-term changes of core origin in the area enclosed by this boundary during 1983–2016. We design a four-step filtering process to minimize the solar contribution to the auroral boundary temporal variation for the northern and southern hemispheres. This process includes filtering geomagnetic and solar activity effects, removal of high-frequency signal, and additional removal of a ~20–30-year dominant solar periodicity. Comparison of our results with the secular change of auroral plus polar cap areas obtained using a simple model of the magnetosphere and a geomagnetic core field model reveals a decent agreement, with area increase/decrease in the southern/northern hemisphere respectively for both observations and model. This encouraging agreement provides observational evidence for the surprising recent decrease of the auroral zone area.

scholarly journals Dilemmas in zirconia bonding: A review

2013 ◽  
Vol 141 (5-6) ◽  
pp. 395-401 ◽  
Author(s):  
Kosovka Obradovic-Djuricic ◽  
Vesna Medic ◽  
Slobodan Dodic ◽  
Dragan Gavrilov ◽  
Djordje Antonijevic ◽  
...  
Keyword(s):  
Bond Strength ◽  
Glass Ceramics ◽  
Ceramic Materials ◽  
The Other ◽  
Zirconia Ceramic ◽  
Bonding Mechanism ◽  
Luting Cements ◽  
Esthetic Dentistry ◽  
Selection Of

This article presents a literature review on the resin bond to zirconia ceramic. Modern esthetic dentistry has highly recognized zirconia, among other ceramic materials. Biocompatibility of zirconia, chemical and dimensional stability, excellent mechanical properties, all together could guarantee optimal therapeutical results in complex prosthodontic reconstruction. On the other hand, low thermal degradation, aging of zirconia as well as problematic bonding of zirconia framework to dental luting cements and tooth structures, opened the room for discussion concerning their clinical durability. The well known methods of mechanical and chemical bonding used on glass-ceramics are not applicable for use with zirconia. Therefore, under critical clinical situations, selection of the bonding mechanism should be focused on two important points: high initial bond strength value and long term bond strength between zirconia-resin interface. Also, this paper emphases the use of phosphate monomer luting cements on freshly air-abraded zirconia as the simplest and most effective way for zirconia cementation procedure today.

scholarly journals Long-term stability analysis and its relationship with the steel structure of gauge blocks from several manufacturers

2021 ◽  
Vol 1193 (1) ◽  
pp. 012077
Author(s):  
A Mínguez ◽  
J Moreno ◽  
J De Vicente
Keyword(s):  
Stability Analysis ◽  
Statistical Method ◽  
Dimensional Stability ◽  
Steel Structure ◽  
Metallographic Analysis ◽  
Measuring Instruments ◽  
Dimensional Metrology ◽  
Long Term Stability ◽  
History Of

Abstract Gauge blocks are one of the most widespread measurement standards (etalons) in dimensional metrology laboratories. Among all its properties, it is worth highlighting the importance of dimensional stability. This property allows to classify these measuring instruments in quality grades. Although the gauge blocks should be dimensionally stable, it can be observed that there is a drift that can be observed when the calibration history is revised. In this document, authors present a statistical method for the estimation of the dimensional stability of gauge blocks using the calibration history of samples from the main manufacturers. In addition, all the samples have been subjected to metallographic analysis to evaluate the structure.

scholarly journals An Analysis of the Optical System of a Length Measurement Comparator

Mechanika ◽  
2020 ◽  
Vol 26 (6) ◽  
pp. 518-525
Author(s):  
Rimantas LAZDINAS ◽  
Mindaugas JUREVICIUS ◽  
Vladas VEKTERIS ◽  
Vytautas TURLA ◽  
Eugenijus JURKONIS
Keyword(s):  
Optical System ◽  
Processing Speed ◽  
Length Measurement ◽  
Identification Algorithm ◽  
High Processing Speed ◽  
Image Blurring ◽  
Scale Calibration ◽  
Calibration Accuracy ◽  
The Impact ◽  
High Processing

In the paper, the optical system of a precise bar length measuring comparator is analysed. The requirements for such a system are determined and systematized. The impact of the resolution, signal discretization frequency, image blurring, bar edge measurement indeterminacy and camera noise on measuring the bar width and establishing the bar position is discussed upon. Various algorithms have been analysed and finally a bar edge identification algorithm oriented to the scale calibration accuracy and the high processing speed was proposed. In the end of the paper, conclusions are provided.

scholarly journals Estimation of free core resonance parameters based on long-term strain observations in the diurnal frequency band

2019 ◽  
pp. 41-50
Author(s):  
V. K. Milyukov ◽  
A. Amoruso ◽  
L. Crescentini ◽  
A. P. Mironov ◽  
A. V. Myasnikov ◽  
...  
Keyword(s):  
Laser Interferometer ◽  
Liquid Core ◽  
Resonant Mode ◽  
Parameter Estimates ◽  
Retrograde Motion ◽  
Tidal Waves ◽  
Superconducting Gravimeters ◽  
Fixed Reference ◽  
Free Core Resonance

The free core nutation (FCN) is one of the Earth’s rotational eigenmodes, which is caused by the retrograde motion of the liquid core relative to the mantle. The FCN period and Q-factor are determined by the elastic properties of the core/mantle boundary (CMB) and their electromagnetic interaction. In the celestial coordinate system, the FCN period is about 430 days; in the Earth-fixed reference frame this effect manifests itself in the form of the free core resonance (FCR) whose frequency falls in the diurnal tidal band. FCR observation requires highly accurate measurement of the amplitudes and phases of the near-diurnal tidal waves. In particular, the parameter estimates for minor waves K1, P1, Ψ1, and Φ1 are critically important for evaluating the FCR effect, i.e., the period and decay of this resonant mode. The progress in the experimental study of FCR is mainly due to the accumulation of the data from superconducting gravimeters and VLBI; at the same time, also the data of the precision laser strainmeters were used. In this work, the FCR effect is studied based on the long-term strain precision records by two European stations: Baksan, Russia (laser interferometer–strainmeter with a measuring armlength of 75 m [Milyukov et al., 2005; 2007] and Gran Sasso, Italy (two perpendicular laser interferometer–strainmeters, BA and BC, each with a measuring armlength of 90 m [Amoruso and Crescentini, 2009]).

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