Extension of measurement range of lubrication gap shape using vertical-objective-type ellipsometric microscopy with two compensator angles

2020 ◽  
Vol 142 ◽  
pp. 105980
Author(s):  
Katsuya Namba ◽  
Kenji Fukuzawa ◽  
Shintaro Itoh ◽  
Hedong Zhang ◽  
Naoki Azuma
Keyword(s):  
Measurement Range ◽  
Objective Type

Low-Loss Images in a Stem/Tem Microscope

1976 ◽  
Vol 34 ◽  
pp. 496-497 ◽  
Author(s):  
David C. Joy ◽  
Dennis M. Maher
Keyword(s):  
High Resolution ◽  
Surface Topography ◽  
Beam Direction ◽  
Low Loss ◽  
Specimen Holder ◽  
Glancing Angle ◽  
High Resolution Images ◽  
Set Up ◽  
Conventional Manner ◽  
Objective Type

High-resolution images of the surface topography of solid specimens can be obtained using the low-loss technique of Wells. If the specimen is placed inside a lens of the condenser/objective type, then it has been shown that the lens itself can be used to collect and filter the low-loss electrons. Since the probeforming lenses in TEM instruments fitted with scanning attachments are of this type, low-loss imaging should be possible.High-resolution, low-loss images have been obtained in a JEOL JEM 100B fitted with a scanning attachment and a thermal, fieldemission gun. No modifications were made to the instrument, but a wedge-shaped, specimen holder was made to fit the side-entry, goniometer stage. Thus the specimen is oriented initially at a glancing angle of about 30° to the beam direction. The instrument is set up in the conventional manner for STEM operation with all the lenses, including the projector, excited.

State special primary acceleration measurement standard for gravimetry GET 190-2019

2020 ◽  
pp. 3-8
Author(s):  
L.F. Vitushkin ◽  
F.F. Karpeshin ◽  
E.P. Krivtsov ◽  
P.P. Krolitsky ◽  
V.V. Nalivaev ◽  
...  
Keyword(s):  
High Precision ◽  
Free Fall ◽  
Measurement Range ◽  
Measurement Standard ◽  
Acceleration Measurement ◽  
Measurement Systems ◽  
Free Fall Acceleration ◽  
Investigation Methods ◽  
Measurement Results ◽  
Upper Level

The State special primary acceleration measurement standard for gravimetry (GET 190-2019), its composition, principle of operation and basic metrological characteristics are presented. This standard is on the upper level of reference for free-fall acceleration measurements. Its accuracy and reliability were improved as a result of optimisation of the adjustment procedures for measurement systems and its integration within the upgraded systems, units and modern hardware components. A special attention was given to adjusting the corrections applied to measurement results with respect to procedural, physical and technical limitations. The used investigation methods made it possibled to confirm the measurement range of GET 190-2019 and to determine the contributions of main sources of errors and the total value of these errors. The measurement characteristics and GET 90-2019 were confirmed by the results obtained from measurements of the absolute value of the free fall acceleration at the gravimetrical site “Lomonosov-1” and by their collation with the data of different dates obtained from measurements by high-precision foreign and domestic gravimeters. Topicality of such measurements ensues from the requirements to handle the applied problems that need data on parameters of the Earth gravitational field, to be adequately faced. Geophysics and navigation are the main fields of application for high-precision measurements in this field.

scholarly journals Influence of the Porosity of Polymer Foams on the Performances of Capacitive Flexible Pressure Sensors

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 1968 ◽  
Author(s):  
Sylvie Bilent ◽  
Thi Hong Nhung Dinh ◽  
Emile Martincic ◽  
Pierre-Yves Joubert
Keyword(s):  
Experimental Data ◽  
Linear Model ◽  
Dielectric Material ◽  
Pressure Sensors ◽  
Volume Ratio ◽  
Measurement Range ◽  
Polymer Foams ◽  
First Order ◽  
Non Linear ◽  
Flexible Pressure Sensors

This paper reports on the study of microporous polydimethylsiloxane (PDMS) foams as a highly deformable dielectric material used in the composition of flexible capacitive pressure sensors dedicated to wearable use. A fabrication process allowing the porosity of the foams to be adjusted was proposed and the fabricated foams were characterized. Then, elementary capacitive pressure sensors (15 × 15 mm2 square shaped electrodes) were elaborated with fabricated foams (5 mm or 10 mm thick) and were electromechanically characterized. Since the sensor responses under load are strongly non-linear, a behavioral non-linear model (first order exponential) was proposed, adjusted to the experimental data, and used to objectively estimate the sensor performances in terms of sensitivity and measurement range. The main conclusions of this study are that the porosity of the PDMS foams can be adjusted through the sugar:PDMS volume ratio and the size of sugar crystals used to fabricate the foams. Additionally, the porosity of the foams significantly modified the sensor performances. Indeed, compared to bulk PDMS sensors of the same size, the sensitivity of porous PDMS sensors could be multiplied by a factor up to 100 (the sensitivity is 0.14 %.kPa−1 for a bulk PDMS sensor and up to 13.7 %.kPa−1 for a porous PDMS sensor of the same dimensions), while the measurement range was reduced from a factor of 2 to 3 (from 594 kPa for a bulk PDMS sensor down to between 255 and 177 kPa for a PDMS foam sensor of the same dimensions, according to the porosity). This study opens the way to the design and fabrication of wearable flexible pressure sensors with adjustable performances through the control of the porosity of the fabricated PDMS foams.

scholarly journals A Resonant Pressure Microsensor with a Wide Pressure Measurement Range

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 382
Author(s):  
Chao Xiang ◽  
Yulan Lu ◽  
Chao Cheng ◽  
Junbo Wang ◽  
Deyong Chen ◽  
...  
Keyword(s):  
Chemical Mechanical Planarization ◽  
Measurement Range ◽  
Silicon On Insulator ◽  
Anodic Bonding ◽  
Pressure Measurements ◽  
Quality Factors ◽  
Deep Reactive Ion Etching ◽  
Wide Range ◽  
Form Pressure ◽  
Silicon Islands

This paper presents a resonant pressure microsensor with a wide range of pressure measurements. The developed microsensor is mainly composed of a silicon-on-insulator (SOI) wafer to form pressure-sensing elements, and a silicon-on-glass (SOG) cap to form vacuum encapsulation. To realize a wide range of pressure measurements, silicon islands were deployed on the device layer of the SOI wafer to enhance equivalent stiffness and structural stability of the pressure-sensitive diaphragm. Moreover, a cylindrical vacuum cavity was deployed on the SOG cap with the purpose to decrease the stresses generated during the silicon-to-glass contact during pressure measurements. The fabrication processes mainly contained photolithography, deep reactive ion etching (DRIE), chemical mechanical planarization (CMP) and anodic bonding. According to the characterization experiments, the quality factors of the resonators were higher than 15,000 with pressure sensitivities of 0.51 Hz/kPa (resonator I), −1.75 Hz/kPa (resonator II) and temperature coefficients of frequency of 1.92 Hz/°C (resonator I), 1.98 Hz/°C (resonator II). Following temperature compensation, the fitting error of the microsensor was within the range of 0.006% FS and the measurement accuracy was as high as 0.017% FS in the pressure range of 200 ~ 7000 kPa and the temperature range of −40 °C to 80 °C.

scholarly journals Frequency synchronization detection method based on adaptive frequency standard tracking

Open Physics ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 434-438
Author(s):  
Xin Geng ◽  
Baoqiang Du ◽  
Jianwei Zhang ◽  
Erlin Tian
Keyword(s):  
Detection Method ◽  
Wide Band ◽  
Frequency Standard ◽  
Frequency Measurement ◽  
Measurement Range ◽  
Period Change ◽  
Measured Signal ◽  
Frequency Synchronization ◽  
Measured Frequency ◽  
Field Programmable

Abstract In order to achieve wide-band high-resolution frequency measurement, a frequency synchronization detection method based on adaptive frequency standard tracking is proposed based on the quantized phase processing. First, the nominal value of the measured frequency signal was obtained from the rough frequency measurement module. Then, the field programmable gate array generated the nominal value of the measured frequency. After that, the direct comparison between the tracking frequency and the measured signal was carried out. Finally, the group quantized processing module gave the final result according to the phase full-period change time. Experimental results showed that the method has a wide frequency measurement range and high accuracy and can obtain frequency stability of the order of 10−13/s.

scholarly journals Measuring Current in a Power Converter Using Fuzzy Automatic Gain Control

2021 ◽  
Vol 11 (13) ◽  
pp. 5793
Author(s):  
Bartosz Dominikowski
Keyword(s):  
High Resolution ◽  
Fuzzy Controller ◽  
Automatic Gain Control ◽  
Gain Control ◽  
Measurement Range ◽  
Power Converter ◽  
Current Measurement ◽  
Dc Power ◽  
Programmable Gain ◽  
Electric Loads

The accuracy of current measurements can be increased by appropriate amplification of the signal to within the measurement range. Accurate current measurement is important for energy monitoring and in power converter control systems. Resistance and inductive current transducers are used to measure the major current in AC/DC power converters. The output value of the current transducer depends on the load motor, and changes across the whole measurement range. Modern current measurement circuits are equipped with operational amplifiers with constant or programmable gain. These circuits are not able to measure small input currents with high resolution. This article proposes a precise loop gain system that can be implemented with various algorithms. Computer analysis of various automatic gain control (AGC) systems proved the effectiveness of the Mamdani controller, which was implemented in an MCU (microprocessor). The proposed fuzzy controller continuously determines the value of the conversion factor. The system also enables high resolution measurements of the current emitted from small electric loads (≥1 A) when the electric motor is stationary.

scholarly journals Dynamic Optimization Method for Broadband ADCP Waveform with Environment Constraints

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3768
Author(s):  
Yongshou Yang ◽  
Shiliang Fang
Keyword(s):  
Distance Estimation ◽  
Acoustic Doppler Current Profiler ◽  
Optimization Method ◽  
Measurement Range ◽  
Velocity Estimation ◽  
Estimation Accuracy ◽  
Dynamic Configuration ◽  
Optimal Velocity ◽  
Flood Warning ◽  
The Impact

Broadband acoustic Doppler current profiler (ADCP) is widely used in agricultural water resource explorations, such as river discharge monitoring and flood warning. Improving the velocity estimation accuracy of broadband ADCP by adjusting the waveform parameters of a phase-encoded signal will reduce the velocity measurement range and water stratification accuracy, while the promotion of stratification accuracy will degrade the velocity estimation accuracy. In order to minimize the impact of these two problems on the measurement results, the ADCP waveform optimization problem that satisfies the environment constraints while keeping high velocity estimation accuracy or stratification accuracy is studied. Firstly, the relationship between velocity or distance estimation accuracy and signal waveform parameters is studied by using an ambiguity function. Secondly, the constraints of current velocity range, velocity distribution and other environmental characteristics on the waveform parameters are studied. For two common measurement applications, two dynamic configuration methods of waveform parameters with environmental adaptability and optimal velocity estimation accuracy or stratification accuracy are proposed based on the nonlinear programming principle. Experimental results show that compared with the existing methods, the velocity estimation accuracy of the proposed method is improved by more than 50%, and the stratification accuracy is improved by more than 22%.

scholarly journals In-Process Diameter Measurement Technique for Micro-Optical Fiber with Standing Wave Illumination

2021 ◽  
Author(s):  
Masaki Michihata ◽  
Zhao Zheng ◽  
Daiki Funaiwa ◽  
Sojiro Murakami ◽  
Shotaro Kadoya ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Standing Wave ◽  
Dynamic Range ◽  
Scattered Light ◽  
High Dynamic Range ◽  
Measurement Range ◽  
Diameter Distribution ◽  
Process Measurement ◽  
Air Turbulence ◽  
Tapered Optical Fiber

AbstractIn this paper, we propose an in-process measurement method of the diameter of micro-optical fiber such as a tapered optical fiber. The proposed technique is based on analyzing optically scattered light generated by standing wave illumination. The proposed method is significant in that it requires an only limited measurement range and does not require a high dynamic range sensor. These properties are suitable for in-process measurement. This experiment verified that the proposed method could measure a fiber diameter as stable as ± 0.01 μm under an air turbulence environment. As a result of comparing the measured diameter distribution with those by scanning electron microscopy, it was confirmed that the proposed method has a measurement accuracy better than several hundred nanometers.

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