In-Situ Tensile Tests of Snow-Pack Layers

AbstractDuring the winter of 1987–88, an average of seven tensile tests was made for each of 66 snow layers in the Rocky Mountains of western Canada. The precision of the mean strength for seven tests, expressed in terms of the coefficient of variation, was 15% with 90% confidence. Snow with a faceted micro-structure was approximately half as strong as partly settled or rounded snow of the same density. Notch sensitivity in the strength data and critical strains of 1% or less indicate that the test fractures were essentially brittle.

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Micromechanical Tensile Testing

MRS Proceedings ◽

10.1557/proc-436-227 ◽

1996 ◽

Vol 436 ◽

Cited By ~ 6

Author(s):

S. Greek ◽

F. Ericson ◽

S. Johansson ◽

J.-Å. Schweitz

Keyword(s):

Fracture Strength ◽

Tensile Testing ◽

Weibull Modulus ◽

Tensile Tests ◽

Cross Sectional ◽

Weibull Statistics ◽

Electrodeposited Nickel ◽

The Mean ◽

Scanning Electron

AbstractA method is described where tensile tests can be performed in situ on micromachined structures. The testing equipment consists of a testing unit mounted on a micromanipulator in a Scanning Electron Microscope (SEM). The fracture loads of micromachined beam structures made from thick and thin film polysilicon as well as from electrodeposited nickel and nickeliron alloy were measured, and the fracture strengths then calculated via measurements of the test structures’ initial cross-sectional areas. The statistical scatter of the polysilicon fracture strength values were evaluated by Weibull statistics. The mean fracture strength and the Weibull modulus, a measure of the scatter, were obtained

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Repeatability and comparability of simulated K values between a grid projection-based device and a Placido/dual Scheimpflug device

Malaysian Journal of Ophthalmology ◽

10.35119/myjo.v2i4.145 ◽

2020 ◽

Vol 2 (4) ◽

pp. 270-280

Author(s):

Julian Matius Tagal

Keyword(s):

Coefficient Of Variation ◽

Ocular Trauma ◽

Mean Difference ◽

Absolute Difference ◽

Limits Of Agreement ◽

The Mean ◽

Mean Differences ◽

The Right

Purpose: To evaluate the repeatability and comparability of simulated K values obtained by the Galilei G4 Corneal Tomographer and the iDesign Wavefront Abberometer. Methods: The right eyes of 100 consecutive pre-laser-assisted in situ keratomileusis (LASIK) patients were included in this study. Patients with a history or signs of previous corneal or ocular trauma and infection were excluded. Paired corneal measurements for flat (K1) and steep (K2) meridians were obtained with both the Galilei and the iDesign. Repeatability was evaluated by calculating the coefficient of variation (CV) of the paired measurements. The comparability between platforms was evaluated by calculation of the mean differences followed by the construction of Bland-Altman plots and calculation of limits of agreement (LOA). Results: While the mean CV for both devices was low (0.17% versus 0.57% for the Galilei and iDesign, respectively), a large proportion of eyes measured by the iDesign (22%) showed an absolute difference of > 0.5 D between paired readings, compared to 1% as measured by the Galilei. The Galilei consistently measured higher than the iDesign. Although the mean difference did not exceed 0.17 D, the LOAs were unacceptablywide at -0.52 D to 0.85 D and -0.69 D to 0.89 D for K1 and K2, respectively. Conclusion: As regards keratometry, the iDesign demonstrated clinically unacceptable repeatability. Both platforms demonstrated sufficiently wide LOA that we could not recommend that they are used interchangeably.

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Analysis of the plastic deformation behavior for two austenitic NiCr-steels with different stacking fault energies

International Journal of Computational Physics Series ◽

10.29167/a1i1p137-141 ◽

2018 ◽

Vol 1 (1) ◽

pp. 137-141

Author(s):

Göran Engberg ◽

Mikael Grehk ◽

Karin Yvell

Keyword(s):

Plastic Deformation ◽

Dislocation Density ◽

Tensile Tests ◽

Stacking Fault ◽

Size Distributions ◽

Stress Strain ◽

Free Distance ◽

The Mean ◽

Stacking Fault Energies

Two austenitic stainless steels, with low and medium stacking fault energies (SFE), 20 mJ/m2 and 30 mJ/m2 respectively, have been studied by conventional tensile tests and in situ tensile tests in a FEG-SEM equipped for EBSD. High angle boundaries (HAB) and low angle boundaries (LAB) with misorientations >= 10o and >= 2o respectively have been determined, and size distributions for the LABs have been derived by linear intercepts. It was found that the size distributions could be described by bimodal lognormal functions. For the steel with highest SFE plastic deformation took place by dislocation slip only while the steel with low SFE deformed by slip and twinning. Using a model for slip based on the evolution of the dislocation density with the generation of dislocations inversely proportional to the mean free distance of slip and recovery of dislocations proportional to the dislocation density the stress strain-curves were analyzed and the results compared with the measured quantities. The mean free distance of slip as evaluated from the stress-strain curve for the steel with the highest SFE correlates very well with the mean size of the LABs intercept. The rate of recovery also gave an expected stress dependence. The stress needed to start deformation twinning was based on the assumption that Shockley partials become completely separated in the slip plane. The thus calculated values for the twinning stress showed an excellent agreement with the observed start of twinning as given by EBSD evaluation of twin boundaries (TB). For the alloy with low SFE both surface grains (in situ test) and bulk grains (from interrupted conventional tests) were studied. The stress needed for slip and twinning of surface grains was, as expected, in the order of 0.5-0.6 times the applied stress.

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Identification of the effective bundle length in a multifilament yarn from the size effect response

Journal of Composite Materials ◽

10.1177/0021998311401068 ◽

2011 ◽

Vol 45 (25) ◽

pp. 2659-2667 ◽

Cited By ~ 2

Author(s):

Rostislav Chudoba ◽

Miroslav Vořechovský ◽

Rostislav Rypl

Keyword(s):

Size Effect ◽

Stress Transfer ◽

Tensile Tests ◽

Specimen Length ◽

Transfer Length ◽

Effect Curve ◽

Mean Size ◽

The Mean ◽

Multifilament Yarn

The article proposes a method for characterizing the in situ interaction between filaments in a multifilament yarn. The stress transfer between neighboring filaments causes the reactivation of a broken filament at some distance from the break. The utilized statistical bundle models predict a change in the slope of the mean size effect curve once the specimen length becomes longer than the stress transfer length. This fact can be exploited in order to determine the stress transfer length indirectly using the yarn tensile test with appropriately chosen test lengths. The identification procedure is demonstrated using two test series of tensile tests with AR-glass and carbon yarns.

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Novel Formulation Development and Evaluation of Nanoparticles Based in Situ Gelling System for The Ophthalmic Delivery of Ciprofloxacin Hydrochloride

International Journal of Drug Delivery Technology ◽

10.25258/ijddt.v5i4.8880 ◽

2015 ◽

Vol 5 (4) ◽

Author(s):

Kranti Singh ◽

Surajpal Verma ◽

Shyam Prasad ◽

Indu Bala

Keyword(s):

Particle Size ◽

Zeta Potential ◽

Drug Loading ◽

In Vitro Release ◽

Formulation Development ◽

Ciprofloxacin Hydrochloride ◽

Potential Value ◽

The Mean ◽

In Situ Gelling

Ciprofloxacin hydrochloride loaded Eudragit RS100 nanoparticles were prepared by using w/o/w emulsification (multiple emulsification) solvent evaporation followed by drying of nanoparticles at 50°C. The nanoparticles were further incorporated into the pH-triggered in situ gel forming system which was prepared using Carbopol 940 in combination with HPMC as viscosifying agent. The developed nanoparticles was evaluated for particle size, zeta potential value and loading efficiency; nanoparticle incorporated in situ gelling system was evaluated for pH, clarity, gelling strength, rheological studies, in-vitro release studies and ex-vivo precorneal permeation studies. The nanopaticle showed the mean particle size varying between 263.5nm - 325.9 nm with the mean zeta potential value of -5.91 mV to -8.13 mV and drug loading capacity varied individually between 72.50% to 98.70% w/w. The formulation was clear with no suspended particles, showed good gelling properties. The gelling was quick and remained for longer time period. The developed formulation was therapeutically efficacious, stable and non-irritant. It provided the sustained release of drug over a period of 8-10 hours.

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Design and development of manually operated gladiolus planter

Journal of AgriSearch ◽

10.21921/jas.v5i01.11135 ◽

2018 ◽

Vol 5 (01) ◽

Author(s):

TAPAN K. KHURA ◽

H. L. KUSHWAHA ◽

SATISH D LANDE ◽

PKSAHOO . ◽

INDRA L . KUSHWAHA

Keyword(s):

Coefficient Of Variation ◽

Field Capacity ◽

Power Source ◽

Forward Speed ◽

Cereal Crop ◽

Maximum Coefficient ◽

Coefficient Of Uniformity ◽

The Mean ◽

The Cost ◽

Immense Potential

Floriculture is an age-old farming activity in India having immense potential for generating selfemployment and income to farmers. However, the cost of cultivation of flower is high as compared to cereal crop. Level of mechanization for different field operations is one but foremost reason for the higher cost of cultivation. As most of the Indian farmers are marginal and small, a need for manually operated gladiolus planter was felt. The geometric properties of gladiolus corm were determined for designing the seed metering system and seed hopper of the planter. The planter was evaluated in the field when pulled by two persons as a power source and guided by a person. The coefficient of variation and highest deviation from the mean spacing was observed as 12.93% and 2.65cm respectively. The maximum coefficient of uniformity of 90.59% was observed for a nominal corm spacing of 15cm at 0.56 kmh-1 forward speed. An average MISS percentage was observed as 2.65 and 2.25 for nominal corm spacing of 15 and 20 cm. The multiple index was zero for two levels corm spacing and forward speed of operation. The QFI was found in the range of 97.2 and 97.9 percent. The average field capacity of the planter was observed as 0.02 hah-1.The average draft requirement of the planter was found as 821 ± 50.3 N.

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Technical note: Inherent benchmark or not? Comparing Nash–Sutcliffe and Kling–Gupta efficiency scores

Hydrology and Earth System Sciences ◽

10.5194/hess-23-4323-2019 ◽

2019 ◽

Vol 23 (10) ◽

pp. 4323-4331 ◽

Cited By ~ 60

Author(s):

Wouter J. M. Knoben ◽

Jim E. Freer ◽

Ross A. Woods

Keyword(s):

Time Series ◽

Coefficient Of Variation ◽

Ad Hoc ◽

Model Performance ◽

Technical Note ◽

Mean Flow ◽

Model Adequacy ◽

Robust Model ◽

The Mean ◽

Adequacy Assessment

Abstract. A traditional metric used in hydrology to summarize model performance is the Nash–Sutcliffe efficiency (NSE). Increasingly an alternative metric, the Kling–Gupta efficiency (KGE), is used instead. When NSE is used, NSE = 0 corresponds to using the mean flow as a benchmark predictor. The same reasoning is applied in various studies that use KGE as a metric: negative KGE values are viewed as bad model performance, and only positive values are seen as good model performance. Here we show that using the mean flow as a predictor does not result in KGE = 0, but instead KGE =1-√2≈-0.41. Thus, KGE values greater than −0.41 indicate that a model improves upon the mean flow benchmark – even if the model's KGE value is negative. NSE and KGE values cannot be directly compared, because their relationship is non-unique and depends in part on the coefficient of variation of the observed time series. Therefore, modellers who use the KGE metric should not let their understanding of NSE values guide them in interpreting KGE values and instead develop new understanding based on the constitutive parts of the KGE metric and the explicit use of benchmark values to compare KGE scores against. More generally, a strong case can be made for moving away from ad hoc use of aggregated efficiency metrics and towards a framework based on purpose-dependent evaluation metrics and benchmarks that allows for more robust model adequacy assessment.

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Investigation of dominant traveling 10-day wave components using long-term MERRA-2 database

Earth Planets and Space ◽

10.1186/s40623-021-01410-7 ◽

2021 ◽

Vol 73 (1) ◽

Author(s):

Chunming Huang ◽

Wei Li ◽

Shaodong Zhang ◽

Gang Chen ◽

Kaiming Huang ◽

...

Keyword(s):

Flow Instability ◽

Transmission Condition ◽

Wave Number ◽

Mean Flow ◽

Excited Wave ◽

Propagating Waves ◽

Zonal Wave Number ◽

The Mean

AbstractThe eastward- and westward-traveling 10-day waves with zonal wavenumbers up to 6 from surface to the middle mesosphere during the recent 12 years from 2007 to 2018 are deduced from MERRA-2 data. On the basis of climatology study, the westward-propagating wave with zonal wave number 1 (W1) and eastward-propagating waves with zonal wave numbers 1 (E1) and 2 (E2) are identified as the dominant traveling ones. They are all active at mid- and high-latitudes above the troposphere and display notable month-to-month variations. The W1 and E2 waves are strong in the NH from December to March and in the SH from June to October, respectively, while the E1 wave is active in the SH from August to October and also in the NH from December to February. Further case study on E1 and E2 waves shows that their latitude–altitude structures are dependent on the transmission condition of the background atmosphere. The presence of these two waves in the stratosphere and mesosphere might have originated from the downward-propagating wave excited in the mesosphere by the mean flow instability, the upward-propagating wave from the troposphere, and/or in situ excited wave in the stratosphere. The two eastward waves can exert strong zonal forcing on the mean flow in the stratosphere and mesosphere in specific periods. Compared with E2 wave, the dramatic forcing from the E1 waves is located in the poleward regions.

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Correlation of Grassy Lake and Cedar Lake ambers using infrared spectroscopy, stable isotopes, and palaeoentomology

Canadian Journal of Earth Sciences ◽

10.1139/e08-049 ◽

2008 ◽

Vol 45 (9) ◽

pp. 1061-1082 ◽

Cited By ~ 40

Author(s):

Ryan C. McKellar ◽

Alexander P. Wolfe ◽

Ralf Tappert ◽

Karlis Muehlenbachs

Keyword(s):

Stable Isotopes ◽

Fourier Transform ◽

Infrared Spectroscopy ◽

Late Cretaceous ◽

Western Canada ◽

Long Distance ◽

Geochemical Fingerprinting ◽

Long Distance Transport ◽

Distance Transport

The Late Cretaceous Grassy Lake and Cedar Lake amber deposits of western Canada are among North America’s most famous amber-producing localities. Although it has been suggested for over a century that Cedar Lake amber from western Manitoba may be a secondary deposit having originated from strata in Alberta, this hypothesis has not been tested explicitly using geochemical fingerprinting coupled to comparative analyses of arthropod faunal content. Although there are many amber-containing horizons associated with Cretaceous coals throughout Alberta, most are thermally mature and brittle, thus lacking the resilience to survive long distance transport while preserving intact biotic inclusions. One of the few exceptions is the amber found in situ at Grassy Lake. We present a suite of new analyses from these and other Late Cretaceous ambers from western Canada, including stable isotopes (H and C), Fourier transform infrared (FTIR) spectra, and an updated faunal compendium for the Grassy and Cedar lakes arthropod assemblages. When combined with amber’s physical properties and stratigraphic constraints, the results of these analyses confirm that Cedar Lake amber is derived directly from the Grassy Lake amber deposit or an immediate correlative equivalent. This enables the palaeoenvironmental context of Grassy Lake amber to be extended to the Cedar Lake deposit, making possible a more inclusive survey of Cretaceous arthropod faunas.

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