Accurate determination of specific heat at high temperatures using the flash diffusivity method

1989 ◽  
Vol 10 (1) ◽  
pp. 251-257 ◽  
Author(s):  
J. W. Vandersande ◽  
A. Zoltan ◽  
C. Wood
Keyword(s):  
Specific Heat ◽  
High Temperatures ◽  
Accurate Determination ◽  
Flash Diffusivity

SPECIFIC HEATS OF MANGANESE AND BISMUTH AT LIQUID HYDROGEN TEMPERATURES

1949 ◽  
Vol 27a (2) ◽  
pp. 9-16 ◽  
Author(s):  
L. D. Armstrong ◽  
H. Grayson-Smith
Keyword(s):  
Specific Heat ◽  
Accurate Determination ◽  
Theoretical Formula ◽  
Electronic Specific Heat ◽  
Debye Function ◽  
Specific Heats ◽  
Simple Cubic ◽  
Limited Temperature ◽  
Specific Heat Coefficient

New measurements of the specific heats of manganese and bismuth in the temperature range 14° to 22° K. are reported. The specific heats of these metals are compared with theory. In both cases the approximate theoretical formula[Formula: see text]where CD(x) is the Debye function, is accurately obeyed over the limited temperature region concerned. However, comparison with measurements at other temperatures shows that this may lead to erroneous conclusions. For manganese a precise conclusion is not possible, and it is estimated that the electronic specific heat coefficient A lies between 0.0035 and 0.0040, while θ varies with temperature from 365 to 390 degrees. For bismuth it is concluded that the electronic specific heat is negligible. This permits an accurate determination of θ, and it is found that the variation of θ with temperature is remarkably similar to that predicted by Blackman for a simple cubic lattice.

Estimating the Thermal Properties of a Calorimeter Using Hierarchical Bayesian Inference With MCMC

2007 ◽  
Author(s):  
A. F. Emery ◽  
D. Bardot
Keyword(s):  
Heat Transfer ◽  
Thermal Properties ◽  
Bayesian Inference ◽  
Specific Heat ◽  
Accurate Determination ◽  
Complex Function ◽  
Thermal Characteristics ◽  
Ambient Conditions ◽  
Hierarchical Bayesian Inference

The accurate determination of the specific heat by placing of a sample in a bath of liquid and measuring the temperature change of the bath and the sample is dependent upon estimation of the heat lost to or gained from the calorimeter. This heat transfer is a complex function of the thermal characteristics of the calorimeter, the initial and ambient conditions, and the convective heat transfer between the bath and the calorimeter walls. This paper describes the estimation of the heat transfer and the determination of the uncertainties in the computed sample specific heat by using Bayesian inference.

scholarly journals The determination of the specific heat of gases at high temperatures by the sound velocity method I―Carbon monoxide

1934 ◽  
Vol 147 (861) ◽  
pp. 292-308 ◽  
Keyword(s):  
Carbon Monoxide ◽  
Specific Heat ◽  
Sound Velocity ◽  
High Temperatures ◽  
Transient Phenomena ◽  
Radiation Correction ◽  
Specific Heats ◽  
Explosion Method

The determination of the specific heats of gases at high temperatures is a problem of unusual difficulty and the attempts hitherto made to measure specific heats at temperatures exceeding 1200° C have been by the "explosion method." This method involves the observation of transient phenomena and also the estimation of a relatively large radiation correction.

scholarly journals The vapour pressure of lead.—I

1923 ◽  
Vol 103 (722) ◽  
pp. 469-486 ◽  
Keyword(s):  
Specific Heat ◽  
Latent Heat ◽  
Vapour Pressure ◽  
Accurate Determination ◽  
Low Pressure ◽  
Sufficient Accuracy ◽  
The Other ◽  
Chemical Constant ◽  
Molten Lead

The accurate determination of the vapour pressure of an element enables many of the other properties to be found, such as the chemical constant, the latent heat of vaporisation, and the change of specific heat with temperature. Unfortunately, the degree of accuracy required for this purpose is very considerable, and only in the case of mercury is the vapour pressure known with sufficient accuracy to determine the chemical constant within 2 per cent. The vapour pressures of zinc and cadmium have previously been determined by the writer, using a method depending on Knudsen's work on the effusion of gases at low pressure. The present paper described an extension of this method to the determination of the vapour pressure of molten lead, and an attempt to improve the accuracy.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Fast calibration of CBED patterns for quantitative analysis

1993 ◽  
Vol 51 ◽  
pp. 674-675
Author(s):  
M.A. Gribelyuk ◽  
M. Rühle
Keyword(s):  
Reciprocal Lattice ◽  
Accurate Determination ◽  
Incident Beam ◽  
Crystal Thickness ◽  
Structure Model ◽  
Beam Direction ◽  
Transmitted Beam ◽  
Reciprocal Vector ◽  
On Line

A new method is suggested for the accurate determination of the incident beam direction K, crystal thickness t and the coordinates of the basic reciprocal lattice vectors V1 and V2 (Fig. 1) of the ZOLZ plans in pixels of the digitized 2-D CBED pattern. For a given structure model and some estimated values Vest and Kest of some point O in the CBED pattern a set of line scans AkBk is chosen so that all the scans are located within CBED disks.The points on line scans AkBk are conjugate to those on A0B0 since they are shifted by the reciprocal vector gk with respect to each other. As many conjugate scans are considered as CBED disks fall into the energy filtered region of the experimental pattern. Electron intensities of the transmitted beam I0 and diffracted beams Igk for all points on conjugate scans are found as a function of crystal thickness t on the basis of the full dynamical calculation.

Computer-Assisted High-Re Solution TEM

1990 ◽  
Vol 48 (1) ◽  
pp. 162-163
Author(s):  
F.A. Ponce ◽  
H. Hikashi
Keyword(s):  
Signal To Noise Ratio ◽  
Accurate Determination ◽  
Computer Software ◽  
Video Camera ◽  
Image Contrast ◽  
Objective Lens ◽  
Computer Assisted ◽  
Optical Parameters ◽  
Astigmatism Correction

The determination of the atomic positions from HRTEM micrographs is only possible if the optical parameters are known to a certain accuracy, and reliable through-focus series are available to match the experimental images with calculated images of possible atomic models. The main limitation in interpreting images at the atomic level is the knowledge of the optical parameters such as beam alignment, astigmatism correction and defocus value. Under ordinary conditions, the uncertainty in these values is sufficiently large to prevent the accurate determination of the atomic positions. Therefore, in order to achieve the resolution power of the microscope (under 0.2nm) it is necessary to take extraordinary measures. The use of on line computers has been proposed [e.g.: 2-5] and used with certain amount of success.We have built a system that can perform operations in the range of one frame stored and analyzed per second. A schematic diagram of the system is shown in figure 1. A JEOL 4000EX microscope equipped with an external computer interface is directly linked to a SUN-3 computer. All electrical parameters in the microscope can be changed via this interface by the use of a set of commands. The image is received from a video camera. A commercial image processor improves the signal-to-noise ratio by recursively averaging with a time constant, usually set at 0.25 sec. The computer software is based on a multi-window system and is entirely mouse-driven. All operations can be performed by clicking the mouse on the appropiate windows and buttons. This capability leads to extreme friendliness, ease of operation, and high operator speeds. Image analysis can be done in various ways. Here, we have measured the image contrast and used it to optimize certain parameters. The system is designed to have instant access to: (a) x- and y- alignment coils, (b) x- and y- astigmatism correction coils, and (c) objective lens current. The algorithm is shown in figure 2. Figure 3 shows an example taken from a thin CdTe crystal. The image contrast is displayed for changing objective lens current (defocus value). The display is calibrated in angstroms. Images are stored on the disk and are accessible by clicking the data points in the graph. Some of the frame-store images are displayed in Fig. 4.

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