New high-speed centre of mass method incorporating background subtraction for accurate determination of fluorescence lifetime

Abstract Objective This study used high-speed cooling of the skin and exact control of stimulus duration to measure the cold detection threshold in healthy participants. The objective was to compare the method of limits, in which the temperature is slowly and gradually increased/decreased until the subject perceives the stimulation, and the method of levels, in which the subject must detect brief thermal stimulations close to the threshold of perception. Methods Twenty healthy volunteers (nine women, 11 men) aged 20–30 years participated in the study. The method of limits and method of levels were performed in all subjects in a counterbalanced order. Four cold detection thresholds were measured with the method of levels, with a temperature ramp of 300°C/sec and stimulus durations of 50 ms, 100 ms, 300 ms, and 500 ms. Three thresholds were measured with the method of limits, with temperature ramps of 1°C/sec, 2°C/sec, and 4°C/sec. Results On average, the cold detection thresholds were −0.47°C below skin temperature with the method of levels and −1.67°C the method of limits. Interindividual variability was significantly lower with the method of levels than with the method of limits. Conclusions These results suggest that the method of levels is more accurate than the method of limits for measuring cold detection threshold. The improvement of cold detection threshold measurement may provide new perspectives to more precisely assess the function of A-delta fibers and the spino-thalamic pathway.

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Experimental device for the accurate determination of wood-water relations on micro-samples

Holzforschung ◽

10.1515/hf.2007.075 ◽

2007 ◽

Vol 61 (4) ◽

pp. 419-429 ◽

Cited By ~ 20

Author(s):

Patrick Perré

Keyword(s):

Moisture Content ◽

Water Relations ◽

High Speed ◽

Growth Ring ◽

Accurate Determination ◽

Longitudinal Direction ◽

Experimental Device ◽

Normal Wood ◽

Diamond Wire Saw

Abstract This paper describes an experimental device designed for the accurate determination of wood/water relations on micro-samples. The moisture content of the sample is measured with a highly sensitive electronic microbalance. Moreover, the dimensions of the sample in tangential and longitudinal direction are collected continuously without contact by means of two high-speed laser scan micrometers. The device is placed in a climatic chamber. The micro-samples investigated were prepared with a diamond wire saw. A sample thickness of less than 1 mm allows the moisture content to be almost uniform during the test. The data obtained are of excellent quality and accuracy, in spite of the very small mass and dimensions of the samples. The device provides a perfect tool for investigating the dynamic interaction between relative humidity, moisture content, and shrinkage. Results collected for beech, spruce and eucalyptus are presented. Important findings include: deviation from a linear relation between shrinkage and moisture content in beech; uniqueness of the shrinkage versus moisture content curve during desorption/adsorption cycles; evidence of cell collapse in eucalyptus, especially for tension wood; and property variations within the growth ring of normal wood and compression wood of spruce.

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Determination of digesta flow entering the omasal canal of dairy cows using different marker systems

British Journal Of Nutrition ◽

10.1079/bjn2003876 ◽

2003 ◽

Vol 90 (1) ◽

pp. 41-52 ◽

Cited By ~ 32

Author(s):

Seppo Ahvenjärvi ◽

Aila Vanhatalo ◽

Kevin J. Shingfield ◽

Pekka Huhtanen

Keyword(s):

Particulate Matter ◽

Liquid Phase ◽

Dairy Cows ◽

High Speed ◽

Volatile Fatty Acids ◽

Accurate Determination ◽

Water Soluble ◽

Neutral Detergent Fibre ◽

Inorganic Matter

Four studies were conducted to compare the effect of four indigestible markers (LiCoEDTA, Yb-acetate, Cr-mordanted straw and indigestible neutral-detergent fibre (INDF)) and three marker systems on the flow of digesta entering the omasal canal of lactating dairy cows. Samples of digesta aspirated from the omasal canal were pooled and separated using filtration and high-speed centrifugation into three fractions defined as the liquid phase, small particulate and large particulate matter. Co was primarily associated with the liquid phase, Yb was concentrated in small particulate matter, whilst Cr and INDF were associated with large particles. Digesta flow was calculated based on single markers or using the reconstitution system based on combinations of two (Co + Yb, Co + Cr and Co + INDF) or three markers (Co + Yb + Cr and Co + Yb + INDF). Use of single markers resulted in large differences between estimates of organic matter (OM) flow entering the omasal canal suggesting that samples were not representative of true digesta. Digesta appeared to consist of at least three phases that tended to separate during sampling. OM was concentrated in particulate matter, whilst the liquid phase consisted mainly of volatile fatty acids and inorganic matter. Yb was intimately associated with nitrogenous compounds, whereas Cr and INDF were concentrated in fibrous material. Current data indicated that marker systems based on Yb in combination with Cr or INDF are required for the accurate determination of OM, N and neutral-detergent fibre flow. In cases where the flow of water-soluble nutrients entering the omasal canal is also required, the marker system should also include Co.

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Sagittal whole-spine magnetic resonance imaging in 750 consecutive outpatients: accurate determination of the number of lumbar vertebral bodies

Journal of Neurosurgery Spine ◽

10.3171/2009.7.spine09326 ◽

2010 ◽

Vol 12 (1) ◽

pp. 47-55 ◽

Cited By ~ 24

Author(s):

Eric H. Hanson ◽

Rahul K. Mishra ◽

David S. Chang ◽

Thomas G. Perkins ◽

Daniel R. Bonifield ◽

...

Keyword(s):

Lumbar Spine ◽

Mr Imaging ◽

High Speed ◽

Imaging System ◽

Accurate Determination ◽

Outpatient Setting ◽

Spine Mr ◽

Vertebral Bodies ◽

Whole Spine

Object When the number of lumbar and sacral vertebrae is being assessed, variations from typical lumbosacral anatomy may confuse the practitioner, potentially leading to significant clinical errors. In this study, the authors describe the statistical variation in lumbar spine anatomy in an outpatient imaging setting, evaluate the potential implications for clinical practice based on the variation in the number of lumbar-type vertebrae identified, and recommend a method for rapidly determining the number of lumbar spine vertebral bodies (VBs) in outpatients referred for lumbar spine MR imaging. Methods A total of 762 patients (male and female) who presented with low back–related medical conditions underwent whole-spine MR imaging in an outpatient setting. Results The high-speed whole-spine evaluation was successful for determining the number of lumbar-type VBs in 750 (98%) of 762 consecutive patients. The sagittal whole-spine 3-T MR imaging system images obtained between the beginning of January 2005 and the end of February 2007 were reviewed. The VBs were counted successively from the level of C-2 inferiorly to the intervertebral disc below the most inferior lumbar-type VB. Numbers of disc herniations were also evaluated in the context of the number of VBs. Conclusions One in 5 of these outpatients did not have 5 lumbar-type vertebrae: 14.5% had 6; 5.3% had 4; and 1 (0.13%) had the rare finding of 3 lumbar-type vertebrae. Two-thirds of the individuals with 6 lumbar-type vertebrae were male and two-thirds of the individuals with 4 lumbar-type vertebrae were female. Sagittal whole-spine MR imaging can be performed rapidly and efficiently in the majority of patients (98%), and provides improved accuracy for the determination of the number of lumbar-type VBs. A supplementary coronal MR, Ferguson view radiograph or intraoperative fluoroscopic determination for the presence of lumbosacral transitional vertebrae may add additional information when indicated for clinical treatment or surgical planning.

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Determination of Dynamic Characteristics of an Impact Forming Machine Structure

Journal of Engineering for Industry ◽

10.1115/1.3439458 ◽

1978 ◽

Vol 100 (4) ◽

pp. 434-440 ◽

Cited By ~ 1

Author(s):

A. E. M. Osman ◽

W. A. Knight ◽

M. M. Sadek

Keyword(s):

Dynamic Characteristics ◽

High Speed ◽

Dynamic Testing ◽

Accurate Determination ◽

Noise Levels ◽

Structural Vibrations ◽

Modes Of Vibration ◽

High Speed Forming ◽

Machine Structure

The noise generated from an impact forming machine arises mainly from structural vibrations and consequently accurate determination of the modal characteristics of the machine is necessary in order to bring about design modifications with the aim of reducing noise levels. Various methods of dynamic testing are applied to a high speed forming machine structure. It is found that the modes of vibration can be successfully identified by impulse tests, with the force pulse generated either by operation of the machine or by means of a hand held hammer.

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Non-Contact Determination of Free Carrier Concentration in n-GaInAsSb

MRS Proceedings ◽

10.1557/proc-799-z3.5 ◽

2003 ◽

Vol 799 ◽

Author(s):

James E. Maslar ◽

Wilbur S. Hurst ◽

Christine A. Wang ◽

Daniel A. Shiau

Keyword(s):

Raman Spectroscopy ◽

Carrier Concentration ◽

High Speed ◽

Near Infrared ◽

Secondary Ion Mass Spectrometry ◽

Accurate Determination ◽

Free Carrier ◽

Hall Measurements ◽

Gaas Substrates

ABSTRACTGaSb-based semiconductors are of interest for mid-infrared optoelectronic and high-speed electronic devices. Accurate determination of electrical properties is essential for optimizing the performance of these devices. However, electrical characterization of these semiconductors is not straightforward since semi-insulating (SI) GaSb substrates for Hall measurements are not available. In this work, the capability of Raman spectroscopy for determination of the majority carrier concentration in n-GaInAsSb epilayers was investigated. Raman spectroscopy offers the advantage of being non-contact and spatially resolved. Furthermore, the type of substrate used for the epilayer does not affect the measurement. However, for antimonide-based materials, traditionally employed Raman laser sources and detectors are not optimized for the analysis wavelength range dictated by the narrow band gap of these materials. Therefore, a near-infrared Raman spectroscopic system, optimized for antimonide-based materials, was developed.Ga0.85In0.15As0.13Sb0.87 epilayers were grown by organometallic vapor phase epitaxy with doping levels in the range 2 to 80 × 1017 cm-3, as measured by secondary ion mass spectrometry. For a particular nominal doping level, epilayers were grown both lattice matched to n-GaSb substrates and lattice-mismatched to SI GaAs substrates under nominally identical conditions. Single magnetic field Hall measurements were performed on the epilayers grown on SI GaAs substrates, while Raman spectroscopy was used to measure the carrier concentration of epilayers grown on GaSb and the corresponding SI GaAs substrates. Contrary to Hall measurements, Raman spectra indicated that the GaInAsSb epilayers grown on GaSb substrates have higher free carrier concentrations than the corresponding epilayers grown on SI GaAs substrates under nominally identical conditions. This is contrary to the assumption that for nominally identical growth conditions, the resulting carrier concentration is independent of substrate, and possible mechanisms will be discussed.

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An Isoparametric Four-Node Beam Element for the Analysis of Planar Robot Manipulators

14th Biennial Conference on Mechanical Vibration and Noise: Vibrations and Dynamics of Robotic and Multibody Structures ◽

10.1115/detc1993-0145 ◽

1993 ◽

Author(s):

Ahmad A. Smaili ◽

Muhammad Sannah

Keyword(s):

High Speed ◽

Structural Characteristics ◽

Accurate Determination ◽

Element Model ◽

Beam Element ◽

Body Motion ◽

Nonlinear Transient ◽

Rigid Joints ◽

Derivatives Of

Abstract Accurate determination of the dynamic response of high speed flexible manipulators requires that the dynamic model incorporates the influence of joint compliances, in addition to faithfully representing the physical characteristics of the links. A finite element model is herein presented for this purpose. The model is based on a 4-node isoparametric Timoshenko beam element to model the structural characteristics of the links including the effects of shear deformation and rotary inertia. It also includes the influence of the rigid body motion and the time derivatives of the elastic deformations of the manipulator on the characteristic matrices of the system, and accounts for the inertia of the drive units and payload and the damping of externally applied dampers. Quasistatic analysis, modal analysis, and linear and nonlinear vibrational responses of a 3-R planar manipulator are determined by solving the appropriate equations of equilibrium. The results of the analysis revealed that the compliance of the joints have a considerable influence on the manipulator response which is manifested by considerable increase in endpoint deflections and substantial decrease in fundamental natural frequency. Nonlinear transient response exhibited a behavior that differs drastically from that obtained when rigid joints are assumed.

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CFD Simulation of Resistance of Highspeed Trimaran Hullforms

10.5957/fast-2015-011 ◽

2015 ◽

Author(s):

Changhwan Son ◽

Prasanta K. Sahoo ◽

Vaibhav Aribenchi ◽

Srikanth Asapana

Keyword(s):

High Speed ◽

Cfd Simulation ◽

Accurate Determination ◽

Cfd Analysis ◽

Test Results ◽

Ansys Fluent ◽

Speed Range ◽

Calm Water ◽

Hull Forms

This paper attempts to carry out a CFD analysis on total resistance for trimaran hull forms based on established NPL systematic series which are high-speed round bilge hull forms. The resistance of high-speed trimaran hull forms have been determined using ANSYS FLUENT, a CFD software package. A systematic series of round bilge demi-hulls were generated, and their resistance in calm water were determined by using ANSYS FLUENT to briefly examine nature and degree of reliability of ANSYS FLUENT. The primary aim of this investigation is to determine resistance characteristics of slender round bilge trimaran hull forms in the high-speed range corresponding to Froude numbers up to 1.0. Model test results obtained from the paper Molland et al (1994) have been used to verify the efficacy of the CFD analysis. The results obtained from CFD have shown considerable promise and further analysis need to be carried out for accurate determination of resistance in trimaran configuration.

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Periodic Discontinuities in the Acceleration of Spheres in Free Flight

Journal of Fluids Engineering ◽

10.1115/1.3448606 ◽

1978 ◽

Vol 100 (1) ◽

pp. 17-21 ◽

Cited By ~ 1

Author(s):

A. L. Tyler ◽

D. L. Salt

Keyword(s):

High Speed ◽

Accurate Determination ◽

Time Derivative ◽

Reynolds Numbers ◽

Low Pressure ◽

Free Flight ◽

Drag Coefficients ◽

Abrupt Changes ◽

Sufficient Precision

The trajectories of unrestrained spheres being accelerated from rest behind a normal shock wave in a shock tube have been recorded by high-speed stroboscopic photography, and precise measurements of the particle positions made with an optical comparator. Data of sufficient precision were obtained to permit the accurate determination of the second time derivative of the particle trajectories. The experiments were conducted in air with plastic spheres ranging in diameter from 0.7 to 2.4 mm and with specific gravities from 0.7 to 1.5. Particle Reynolds numbers from 1 × 104 to 5 × 104 were obtained, and absolute particle accelerations from 1 × 106 to 5 × 106 ± 0.16 × 106 cm/s2 were measured. The relative velocities were all subsonic; relative Mach numbers ranged from 0.3 to 0.6. The values of the particle acceleration, when plotted as a function of time, were found to contain periodic abrupt changes similar to a mathematical discontinuity. It is postulated that the associated abrupt changes in the forces exerted on the particles are caused by periodic detachment of low-pressure centers of vorticity which form behind the spheres. Values of the drag coefficients determined from the data similarly exhibit periodic abrupt changes. These changes appear, in the way they consistently increase during each cycle of the period and fall at the point of “discontinuity,” to be compatible with the postulate that the periodic behavior is caused by formation and abrupt detachment of low-pressure vortices in the wake. Values of the drag coefficients were found to vary from 10 percent to 30 percent above steady-state values at comparable Reynolds numbers—the range of the computed values of the drag coefficient being caused by the periodic nature of the quantity.

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