Load cells ensure a perfect colour match

Abstract The availability of the focused ion beam (FIB) microscope with its excellent imaging resolution, depth of focus and ion milling capability has made it an appealing platform for materials characterization at the sub-micron, or "nano" level. This article focuses on nanomechanical characterization in the FIB, which is an extension of the FIB capabilities into the realm of nano-technology. It presents examples that demonstrate the power and flexibility of nanomechanical testing in the FIB or scanning electron microscope with a probe shaft that includes a built-in strain gauge. Loads that range from grams to micrograms are achievable. Calibration is limited only by the availability of calibrated load cells in the smallest load ranges. Deflections in the range of a few nanometers range can be accurately applied. Simultaneous electrical, mechanical, and visual data can be combined to provide a revealing study of physical behavior of complex and dynamic nanostructures.

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Design and Calibration of Robot Base Force/Torque Sensors and Their Application to Non-Collocated Admittance Control for Automated Tool Changing

Sensors ◽

10.3390/s21092895 ◽

2021 ◽

Vol 21 (9) ◽

pp. 2895

Author(s):

Hubert Gattringer ◽

Andreas Müller ◽

Philip Hoermandinger

Keyword(s):

Steel Plate ◽

Robotic Manipulators ◽

Indirect Measurement ◽

Local Deformation ◽

Contact Forces ◽

The Novel ◽

Admittance Control ◽

Load Cells ◽

Series Elastic Actuators ◽

Automated Tool

Robotic manipulators physically interacting with their environment must be able to measure contact forces/torques. The standard approach to this end is attaching force/torque sensors directly at the end-effector (EE). This provides accurate measurements, but at a significant cost. Indirect measurement of the EE-loads by means of torque sensors at the actuated joint of a robot is an alternative, in particular for series-elastic actuators, but requires dedicated robot designs and significantly increases costs. In this paper, two alternative sensor concept for indirect measurement of EE-loads are presented. Both sensors are located at the robot base. The first sensor design involves three load cells on which the robot is mounted. The second concept consists of a steel plate with four spokes, at which it is suspended. At each spoke, strain gauges are attached to measure the local deformation, which is related to the load at the sensor plate (resembling the main principle of a force/torque sensor). Inferring the EE-load from the so determined base wrench necessitates a dynamic model of the robot, which accounts for the static as well as dynamic loads. A prototype implementation of both concepts is reported. Special attention is given to the model-based calibration, which is crucial for these indirect measurement concepts. Experimental results are shown when the novel sensors are employed for a tool changing task, which to some extend resembles the well-known peg-in-the-hole problem.

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The One-Year In Vivo Comparison of Lithium Disilicate and Zirconium Dioxide Inlays

Materials ◽

10.3390/ma14113102 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3102

Author(s):

Rini Behera ◽

Lora Mishra ◽

Darshan Devang Divakar ◽

Abdulaziz A. Al-Kheraif ◽

Naomi Ranjan Singh ◽

...

Keyword(s):

Zirconium Dioxide ◽

Clinical Performance ◽

Lithium Disilicate ◽

Study Groups ◽

Resin Cement ◽

Internal Surfaces ◽

Colour Match ◽

One Year ◽

The One

The objective of the present study was to evaluate the one-year clinical performance of lithium disilicate (LD) and zirconium dioxide (ZrO2) class II inlay restorations. Thirty healthy individuals who met the inclusion criteria were enrolled for the study. The patients were randomly divided into two study groups (n = 15): LD (IPS e.max press) and ZrO2 (Dentcare Zirconia). In the ZrO2 group, the internal surfaces of the inlays were sandblasted and silanized with Monobond N (Ivoclar, Leichsteistein, Germany). In the LD group, the internal surfaces of the inlays were etched with 5% hydrofluoric acid. The ceramic inlays were cemented with self-cure resin cement (Multilink N). Clinical examinations were performed using modified United State Public Health Codes and Criteria (USPHS) after 2 weeks, 4 weeks, 6 months and 1 year. The one-year survival rate was evaluated. In total, one failure was observed in the ZrO2 group. The survival probability after 1 year for the ZrO2 inlays was 93%, and for the LD inlays was 100%, which was statistically insignificant. The differences between both groups for most USPHS criteria (except for colour match) were statistically insignificant. Within the imitations of the present study, the lithium disilicate- and zirconia dioxide-based inlays exhibited comparable clinical performances. However, the colour and translucency match was superior for the lithium disilicate restorations.

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Birds colour-match their nests

Nature ◽

10.1038/514276c ◽

2014 ◽

Vol 514 (7522) ◽

pp. 276-276

Keyword(s):

Colour Match

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Experimental and Theoretical Rotordynamic Characteristics of a Hybrid Journal Bearing

Journal of Tribology ◽

10.1115/1.2832446 ◽

1997 ◽

Vol 119 (1) ◽

pp. 132-141 ◽

Cited By ~ 17

Author(s):

J. T. Sawicki ◽

R. J. Capaldi ◽

M. L. Adams

Keyword(s):

Journal Bearing ◽

Operating Conditions ◽

Dynamic Force ◽

Test Results ◽

Force Measurements ◽

Lubrication Equation ◽

Load Cells ◽

Theoretical Predictions ◽

Stiffness And Damping

This paper describes an experimental and theoretical investigation of a four-pocket, oil-fed, orifice-compensated hydrostatic bearing including the hybrid effects of journal rotation. The test apparatus incorporates a double-spool-shaft spindle which permits independent control over the journal spin speed and the frequency of an adjustable-magnitude circular orbit, for both forward and backward whirling. This configuration yields data that enables determination of the full linear anisotropic rotordynamic model. The dynamic force measurements were made simultaneously with two independent systems, one with piezoelectric load cells and the other with strain gage load cells. Theoretical predictions are made for the same configuration and operating conditions as the test matrix using a finite-difference solver of Reynolds lubrication equation. The computational results agree well with test results, theoretical predictions of stiffness and damping coefficients are typically within thirty percent of the experimental results.

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COLOUR-MATCHING IN HAND AND FINGER PROSTHESES: THE ASIAN PERSPECTIVE

Hand Surgery ◽

10.1142/s0218810496000099 ◽

1996 ◽

Vol 01 (01) ◽

pp. 37-43 ◽

Cited By ~ 9

Author(s):

Eng-Lye Leow ◽

Anam-Kueh Kour ◽

Barry P. Pereira ◽

Robert W.H. Pho

Keyword(s):

Asian Population ◽

Hand Prosthesis ◽

Custom Made ◽

Wide Range ◽

Colour Match ◽

Matching Procedure

The wide range of skin tones in the Asian population presents a challenge when colour-matching hand and finger prostheses. It requires that the prostheses be custom-made to better match the wide variations. We have developed a finger and hand prosthesis using a multi-layered moulding technique incorporating a colour-matching procedure capable of reproducing the colour tones and life-like appearance of the skin. Between 1990–1994, we have fitted these prostheses to a total of 109 patients. In evaluating the colour-match of their prostheses, 84% of the patients fitted with hand prostheses and 78% of those fitted with finger prostheses had a good to excellent match. This paper discusses some of the challenges we face in colour-matching hand and finger prostheses in the Asian population.

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Validation of Mooring Simulations (for Mooring Integrity Assessment) With In-Service Tension Measurements

10.1115/omae2021-62772 ◽

2021 ◽

Author(s):

Willemijn Pauw ◽

Remco Hageman ◽

Joris van den Berg ◽

Pieter Aalberts ◽

Hironori Yamaji ◽

...

Keyword(s):

Numerical Models ◽

Weather Conditions ◽

Mooring Line ◽

Mooring System ◽

Mooring Lines ◽

Data Set ◽

Integrity Assessment ◽

Motion Data ◽

Load Cells ◽

Line Loads

Abstract Integrity of mooring system is of high importance in the offshore industry. In-service assessment of loads in the mooring lines is however very challenging. Direct monitoring of mooring line loads through load cells or inclinometers requires subsea installation work and continuous data transmission. Other solutions based on GPS and motion monitoring have been presented as solutions to overcome these limitations [1]. Monitoring solutions based on GPS and motion data provide good practical benefits, because monitoring can be conducted from accessible area. The procedure relies on accurate numerical models to model the relation between global motions and response of the mooring system. In this paper, validation of this monitoring approach for a single unit will be presented. The unit under consideration is a turret-moored unit operating in Australia. In-service measurements of motions, GPS and line tensions are available. A numerical time-domain model of the mooring system was created. This model was used to simulate mooring line tensions due to measured FPSO motions. Using the measured unit response avoids the uncertainty resulting from a prediction of the hydrodynamic response. Measurements from load cells in various mooring lines are available. These measurements were compared against the results obtained from the simulations for validation of the approach. Three different periods, comprising a total of five weeks of data, were examined in more detail. Two periods are mild weather conditions with different dominant wave directions. The third period features heavy weather conditions. In this paper, the data set and numerical model are presented. A comparison between the measured and numerically calculated mooring line forces will be presented. Differences between the calculated and measured forces are examined. This validation study has shown that in-service monitoring of mooring line loads through GPS and motion data provides a new opportunity for mooring integrity assessment with reduced monitoring system complexity.

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Improvements in Data Acquisition for Propulsion Shaft Alignment

10.5957/pss-2015-008 ◽

2015 ◽

Author(s):

W. David Joiner ◽

Charles J. Cook

Keyword(s):

Data Acquisition ◽

Strain Gage ◽

Strain Gages ◽

Construction Process ◽

Crucial Step ◽

Ship Construction ◽

Shaft Line ◽

Load Cells ◽

Shaft Alignment

Propulsion shaft alignment is a necessary and crucial step in the ship construction process, with manning and schedule constraints requiring accurate results as efficiently as possible. There are two methods for measuring the bearing loading along the shaft line: strain gages and load cells. The legacy method for using strain gages required a lot of man power and the legacy method for using load cells was dependent on the quality of machinist made available. Strain gages are the transducers of choice for measurement; however the data acquisition, especially for ships with long shafting systems, can require many strain gage positions and personnel to conduct tests. Load cells are used to validate the accuracy of the strain gage method and to calculate the shaft runout at each bearing location.

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