The AC-Indentation Technique and its Application to Al and Al-Si Coatings

1991 ◽  
Vol 226 ◽  
Author(s):  
T.W. Wu
Keyword(s):  
Penetration Depth ◽  
High Sensitivity ◽  
Small Displacement ◽  
Depth Profiles ◽  
Indentation Technique ◽  
Indentation Process ◽  
Microindentation Technique ◽  
Penetration Depths ◽  
Selection Of

AbstractAn ac-microindentation technique, namely indenting with a small displacement modulation superimposed on an otherwise linear indenter motion, will be introduced. The basic principle and theory will also be illustrated by using a mechanical model to simulate the indenter behavior.Other than being as capable as conventional indentation, the ac-technique acquires the unloading slope simultaneously and continuously with the penetration depth and applied load during an entire indentation process. With this extra information, the conversion between the total depth and plastic depth can be executed right after a single indentation, and in turn the hardness as well as. contact modulus depth profiles can be calculated. This is in contrast to the conventional indentation technique where a group of indentations associated with different maximum loads are required in order to achieve the same purpose. Furthermore, it also avoids the subjectivity in the selection of the fitting portions from the unloading stage of an indentation curve to extract the unloading slopes as well as the plastic penetration depths.Another important advantage of using this ac-technique is the high sensitivity in detecting the indenter/surface contact. This advantage is very useful in the determination of the origins of penetration depths as well as in the investigation the evolution of the contact area, and both issues are very crucial in the microhardness calculations.The strain rate effect on the hardness measurements of a 1 μm thick Al-2%Si coating has been demonstrated by using the ac-technique. As the indenter loading speed increases from 2.5 to 10 nm/sec, the measured hardness of the coating can be increased from ∼20% to ∼80% depending on the penetration depth, and the shallower the penetration depth the larger the increment is. However, the contact modulus depth profiles remain unchanged for all the indentation rates.

scholarly journals Determination of Histamine in Tomatoes by Capillary Electrophoresis

2000 ◽  
Vol 83 (1) ◽  
pp. 89-94 ◽  
Author(s):  
Elek Bolygo ◽  
Paul A Cooper ◽  
K Michael Jessop ◽  
Frank Moffatt
Keyword(s):  
Capillary Electrophoresis ◽  
Signal To Noise Ratio ◽  
High Sensitivity ◽  
Flow Cell ◽  
Voltage Gradient ◽  
Signal To Noise ◽  
Tomato Fruits ◽  
Endogenous Level ◽  
Selection Of

Abstract An improved capillary electrophoresis assay for histamine in crude extracts was developed and used to determine histamine levels in a selection of tomato fruits and pastes. Performance in terms of reproducibility and sensitivity was optimized by use of a high sensitivity detector flow cell, sodium hydroxide rinses, and a voltage gradient. The method was linear down to 0.2 μg/mL (signal-to-noise ratio = 4:1), which was below the endogenous level in all samples.

Stray light and ghosts in catadioptric spectrometers: incorporating grating scatter measurements into simulations and ghost sensitivity into system design

2018 ◽  
Vol 7 (6) ◽  
pp. 377-386 ◽  
Author(s):  
Monika Kroneberger ◽  
Andreas Mezger ◽  
Stephanie Becker
Keyword(s):  
High Sensitivity ◽  
Stray Light ◽  
Multiple Diffraction ◽  
Optical Elements ◽  
Optical Instruments ◽  
Light Requirements ◽  
Measurement Results ◽  
Selection Of

Abstract The accurate simulation of stray light is essential for the verification of the contrast requirements in optical instruments. In a spectrometer, the scattering from reflective gratings is difficult to characterize while contributing significantly to the overall system stray light and reduction of the spectrometer contrast. In addition, the multiple diffraction orders create a ghost sensitive environment, which must be considered in the design of the instrument. In this article, we present an experimental setup for, and measurement results from, the characterization of the bidirectional scattering distribution function (BSDF) of a holographic grating for a spectrometer applied in a typical earth observation mission with demanding stray light requirements. We observed distinct stray light peaks out of the diffraction plane, which are called ‘satellites.’ The main challenges in the measurement of grating BSDFs arise from the near angle limit, the determination of the instrument signature and the selection of the appropriate sampling (2D or 3D). Following the grating characterization, the next step is to introduce these measured BSDFs into stray light simulation. We have done that by fitting appropriate functions to the measured BSDF and defining them in the optical analysis software ASAP as a user-defined BSDF. Ghost analysis is done at the spectrometer level as a sensitivity analysis of the tilts of the optical elements. Due to the ghosting of higher diffraction orders of the grating, a high sensitivity to the tilts of some of the optical elements can be seen.

scholarly journals Selection of Suitable Data Sets Improves 230Th/U Dates of Dirty Material

2008 ◽  
Vol 30 (-1) ◽  
pp. 69-77 ◽  
Author(s):  
Mebus Geyh
Keyword(s):  
Isotope Ratio ◽  
Activity Ratio ◽  
Uranium Concentration ◽  
Ash Content ◽  
Age Dating ◽  
Data Sets ◽  
Selection Procedures ◽  
Depth Profiles ◽  
Selection Of

Selection of Suitable Data Sets Improves230Th/U Dates of Dirty Material230Th/U dating of dirty material such as fen peat and secondary carbonates depends on the ability to select suitable and to discard unsuitable data sets before the calculation of230Th/U ages. This means that open system conditions with respect to uranium during ageing are excluded and solely one source of detrital contamination was present in the samples. Three kinds of selection approaches of suitable data sets were applied: (1) isotope ratio plots, (2) the isotope-ratio evolution plot and the iterative determination of the decay-corrected initial detrital230Th/232Th activity ratio (AR) as well as (3) depth profiles of the uranium concentration and the234U/238U AR and the ash content. For reliable230Th/U age dating of dirty material all selection procedures have to be commonly applied because none of them works perfectly.

A linear log d – log w model for the determination of consistency limits of soils

2001 ◽  
Vol 38 (6) ◽  
pp. 1335-1342 ◽  
Author(s):  
Tao-Wei Feng
Keyword(s):  
Water Content ◽  
Penetration Depth ◽  
Flow Curve ◽  
Linear Regression Analysis ◽  
Liquid Limit ◽  
Plastic Limit ◽  
Cone Penetration ◽  
Data Points ◽  
Penetration Depths

A linear logarithm–logarithm model for the fall cone penetration depth versus water content relationship (flow curve) has been developed based on the results of an experimental study using the British fall cone apparatus. The fall cone flow curve is expressed by a simple equation with parameters m and c, which represent the slope of the flow curve and the water content at a penetration depth of 1 mm, respectively. For a soil, the flow curve can be determined by applying a linear regression analysis to at least four data points with penetration depths approximately evenly distributed between 25 and 3 mm. It is shown in this paper that both the liquid limit and the plastic limit determined from the linear logarithm–logarithm flow curve are in close agreement with those determined from conventional methods. A one-point method for determination of the liquid limit is developed from the model and is verified by applying statistical analysis to a large volume of experimental data.Key words: fall cone, laboratory tests, consistency limits, clays.

Atomic absorption determination of Hg (II), Cd (II), and As (III) in natural and waste water after preliminary group preconcentration

2019 ◽  
Vol 85 (2) ◽  
pp. 12-16
Author(s):  
I. V. Saunina ◽  
E. N. Gribanov ◽  
E. R. Oskotskaya
Keyword(s):  
Waste Water ◽  
Atomic Absorption ◽  
High Sensitivity ◽  
Distribution Coefficients ◽  
Neutral Medium ◽  
Atomic Absorption Determination ◽  
Absorption Determination ◽  
Relative Standard ◽  
Preliminary Group

The sorption of Hg (II), Cd (II), and As (III) by natural aluminosilicate is studied. It is shown that the mineral absorbs those toxicants in a rather wide pH range, quantitative extraction of analytes being achieved in a neutral or close to neutral medium (pH values range within 7.0 - 8.0; 6.3 - 7.5; 7.4 - 8.5 for Hg (II), As (III), and Cd (II), respectively). The effect of the time of phase contact on the degree of extraction of elements is shown. The sorption capacity of the mineral in optimal conditions of the medium acidity (0.06 mmol/g for mercury, 0.31 mmol/g for cadmium, and 0.52 mmol/g for arsenic) is determined. The distribution coefficients attain values of aboutnX 103-nX 104. A new combined method for determination of Hg (II), Cd (II), and As (III) in natural and waste water is developed and tested. The method consists in a preliminary group sorption concentration of the analytes by aluminosilicate, desorption of the analytes from the surface of the mineral and their subsequent atomic absorption determination. The correctness of the method is verified in analysis of spiked samples. The method is easy to use and exhibits high sensitivity, reproducibility and accuracy of analyte determination. The relative standard deviation does not exceed 0.13. Economic availability and possibility of using domestic sorption materials are the important advantages of the proposed procedure which can be used in the practice of laboratories monitoring the quality and safety of environmental objects.

DETERMINING THE DESALINATION UNIT COMPOSITION FOR COSTAL AREAS AND SMALL ISLANDS USE ANALYTIC HIERARCHY PROCESS

2017 ◽  
Vol 9 (1) ◽  
Author(s):  
Imam Setiadi ◽  
Dinda Rita K. Hartaja
Keyword(s):  
Analytic Hierarchy Process ◽  
Energy Demand ◽  
Pairwise Comparison ◽  
Small Islands ◽  
Ahp Method ◽  
Analytic Hierarchy ◽  
Comparison Research ◽  
Hierarchy Process ◽  
Selection Of

Selection of the appropriate composition desalination units can be done with a variety of method approaches, one of the method is the Analytic Hierarchy Process. In determining the desalination unit with AHP method to consider is setting a goal, an alternative criteria and pairwise comparison. Research for the determination of the exact composition of the desalination unit in order to achieve sustainable drinking water suppy in coastal areas and small islands has been conducted. The results of the study are as follows, the energy demand of 50.83%, operator costs of 26.64%, maintenance costs of 14.13% and chemical requirement 8.4%. For an alternative composition desalination unit of RO 10 m3 / day is the best alternative composition with value of 59.61%, the composition of the next alternative is RO 20 m3/ day of 30.40% and the last alternative of the desalination unit composition is RO 120 m3/ day of 09.99%.Key words : Desalination, Mukti Stage Flash Composition, AHP

Optimization of the selection of analysis methods for the determination of naturally occurring radionuclides

Kerntechnik ◽  
2008 ◽  
Vol 73 (3) ◽  
pp. 118-121
Author(s):  
T. Heinrich ◽  
L. Funke ◽  
M. Köhler ◽  
U.-K. Schkade ◽  
F. Ullrich ◽  
...  
Keyword(s):  
Naturally Occurring ◽  
Analysis Methods ◽  
Naturally Occurring Radionuclides ◽  
Selection Of
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