17 Result(s)

Article

Microwave-Dimensional Measurements of Cylindrical Resonators for Primary Acoustic Thermometry

Acoustic gas thermometry relies on the fundamental relationship between the speed of sound in a monatomic gas and its thermodynamic temperature. The speed of sound is calculated from the resonance frequencies ...

R. J. Underwood, G. J. Edwards in International Journal of Thermophysics (2014)

Article

A Novel Comparative Photothermal Method for Measuring Thermal Diffusivity

A novel comparative method has been developed at the National Physical Laboratory (NPL) to measure the thermal diffusivity of semi-infinite samples without a priori knowledge of the boundary conditions. It is bas...

M. Broussely, A. P. Levick, G. J. Edwards in International Journal of Thermophysics (2005)

Article

Measurement of the Thermal Diffusivity of Solids with an Improved Accuracy

A photothermal radiometry technique is being developed at the NPL with the goal of improving the accuracy of thermal diffusivity measurements. The principle is to perform a laser-induced thermal experiment whi...

C. D. Martinsons, A. P. Levick, G. J. Edwards in International Journal of Thermophysics (2003)

Chapter and Conference Paper

A Unified Framework for Atlas Matching Using Active Appearance Models

We propose to use statistical models of shape and texture as deformable anatomical atlases. By training on sets of labelled examples these can represent both the mean structure and appearance of anatomy in med...

T. F. Cootes, C. Beeston, G. J. Edwards… in Information Processing in Medical Imaging (1999)

Article

Radiation Damage Mechanisms In Scintillator Materials: Applications to BaF₂ and CeF₃

Results from recent radiation damage studies in high quality BaF₂ and CeF₃ crystals are presented. Optical absorption and electron paramagnetic resonance (EPR) techniques are used to identify specific radiation d...

L. E. Halliburton, G. J. Edwards in MRS Online Proceedings Library (1994)

Article

A temperature-dependent dispersion equation for congruently grown lithium niobate

G. J. Edwards, M. Lawrence in Optical and Quantum Electronics (1984)

Article

Stable clocks and the theory of relativity

G.J. Edwards in Nature (1981)

Article

Frequency of the methane-stabilized He–Ne laser at 88 THz measured to ±3 parts in 10¹¹

We have measured the frequency of methane-stabilized laser at 88 THz (3.39 µm) (ref. 1), by method which largely eliminates the uncertainties contributed by lower-frequency lasers used as transfer oscillators....

D. J. E. Knight, G. J. Edwards, P. R. Pearce, N. R. Cross in Nature (1980)

Article

Dislodgeable residues of parathion and carbophenothion in florida citrus: A weather model

H. N. Nigg, J. C. Allen, R. W. King… in Bulletin of Environmental Contamination an… (1978)

Article

Dislodgeable residues of ethion in Florida citrus and relationships to weather variables

Five different treatments of ethion on Valencia orange trees were compared for decay rates and for ethion monoxon and ethion dioxon production under different environmental conditions. The oxon metabolite leve...

H. N. Nigg, J. C. Allen, R. F. Brooks… in Archives of Environmental Contamination an… (1977)

Article

Measurement of the frequency of the methane-stabilised laser at 3.39 µm and of the R(32) transition of CO₂ at 10.17 µm

ACCURATE, infrared, frequency and wavelength measurements now constitute the best means of determining the speed of light, and provide a link between the standards of length and time. We measured the frequency...

T. G. BLANEY, C. C. BRADLEY, G. J. EDWARDS, B. W. JOLLIFFE, D. J. E. KNIGHT… in Nature (1975)

Chapter and Conference Paper

Progress with a Determination of the Speed of Light

The scheme for measuring the CO₂ laser frequency (shown in the Introduction) consists of three separate frequency-mixing experiments using two lower-frequency lasers as transfer oscillators. If an accurate measur...

T. G. Blaney, C. C. Bradley, G. J. Edwards… in Atomic Masses and Fundamental Constants 4 (1972)

Chapter and Conference Paper

Progress with a Determination of the Speed of Light

Until recently the direct measurement of frequencies in the infra-red spectral region has not been possible because of the lack of suitable detectors and mixers with response times of the order of 10⁻¹³ to 10⁻¹⁴ ...

C. C. Bradley, G. J. Edwards, D. J. E. Knight in Atomic Masses and Fundamental Constants 4 (1972)