Problem Of Temperature Measurement Research Articles

Non-contact multiband method for emissivity measurement

During the last decade an increasing interest in passive multiband systems for temperature measurement was noted and quite a few such systems have been developed. However, recent studies showed that multiband systems are capable of producing accurate results of non-contact temperature measurement only in limited number of applications and that multiband systems will not become a real rival for single band systems in temperature measurement applications. Available literature about passive multiband systems concentrated exclusively on the problem of temperature measurements with these systems in situation when these systems can be used for non-contact emissivity measurements too. A model of a passive multiband system for non-contact emissivity measurement has been developed in this paper. Simulations carried out using this model showed that it is possible to achieve reasonable accuracy of emissivity measurements with passive multiband systems and these systems can be considered as an attractive solution for emissivity measurements in industrial conditions.

A new computer method for temperature measurement based on an optimal control problem

A new computer method to measure extreme temperatures is presented. The method reduces the measurement of the unknown temperature to the solving of an optimal control problem, using a numerical computer. Based on this method, a new device for temperature measurement is built. It consists of a hardware part that includes some standard temperature sensors and it also has a software section. The problem of temperature measurement, according to this new method, is mathematically modelled by means of the one-dimensional heat equation, with boundary and initial conditions, describing the heat transfer through the device. The principal hardware component of the new device is a rod. The variation of the temperature which is produced near one end of the rod is determined using some temperature measurements in the other end of the rod and the new computer method which is described in this work. This device works as an attenuator of high temperatures and as an amplifier of low temperatures. In fact, it realizes an extension of the standard working range of temperature sensors at very high and very low values. The mathematical model of the device and the computer method are explained in detail and some possible practical implementations and a collection of simulations are also presented.

A new technique of high-temperature diffractometry of glass melts

A high-temperature device is described which allows wide-angle x-ray scattering experiments (WAXS) of molten glasses in transmission arrangement without parasitic scattering and problems due to chemical reactions. The advantage of high heating and cooling rates for glass melt studies is emphasized and problems of temperature measurement and homogeneity are discussed.

A hot stage SEM for gas‐solid reaction studies

An ultra‐high vacuum, field emission source, scanning electron microscope (SEM) equipped with a gas cell to permit the in situ study of high temperature gas‐solid reactions is described.High resolution SEM (50 Å) and scanning Auger microscopy (300 Å resolution) can be carried out at specimen temperatures up to 1000°C. Reaction products and processes can be imaged continuously in the SEM at pressures up to ∼0.2 Torr. Gas pressures up to 50 Torr are possible but with some limitations.Methods of specimen mounting, problems of temperature measurement, and the microscope performance at high specimen temperatures and gas pressures are discussed. Examples of metal surface preparation and impurity segregation under high temperature annealing and gas exposure are reported.

Etude magnetothermoélectrique de la transition métal-semiconducteur dans les composés Cr 2+ εSe 3 (0 ≤ ε ≤ 0,04) : I. Dispositif de mesure de l'effet Nernst longitudinal

Experimental equipment is described which permits the measurement of the thermoelectric power (TEP) between 5 and 300 K in a magnetic field (longitudinal Nernst effect) up to 10 T. It is to be used to study thoroughly the metal-semiconductor transition in Cr 2+εSe 3 which encompasses n-type semiconductors and p-type metallic compounds. The delicate problem of temperature measurements below 20 K, in a magnetic field, has been solved by the use of “Carbon-Glass” resistance sensors which have exhibited high sensitivity and reproducibility in high magnetic fields. At 5 K, the very small temperature difference (about 0.5 K) between the sides of the sample is measured with an accuracy better than 3%. The TEP in a magnetic field is obtained with an accuracy of approximately 5%.

Simplified Laplace Transform Inversion for Unsteady Surface Element Method for Transient Conduction

The unsteady surface element method is an analytical procedure for solving certain types of transient heat conduction problems. The method is intended for thermally contacting bodies of similar or dissimilar geometries such as occur in the contact conductance, fin, and temperature measurement problems. The method utilizes Duhamel's integral. The two simplified procedures in this paper utilize an approximate inverse Laplace transform relation given by Schapery to obtain functional forms of the solutions. In certain cases the approximate inverse Laplace relations simplify the solution greatly and produce acceptable accuracy. Tauberian, series, and numerical tests define these successful cases. The results presented are useful for the intrinsic thermocouple problem and as background for more general heat conduction problems.

New Aspects to the Problem of Temperature Measurement in Rising Flexible Polyether-Polyurethane Foams

New Aspects to the Problem of Temperature Measurement in Rising Flexible Polyether-Polyurethane Foams

Problems in High Temperature Thermometry

The discussion is presented under the following subject headings: temperature and temperature scales; calibration tactics; resistance thermometry; thermocouple thermometry; pyrometry; and other types of thermometers. The discussion is concerned primarily with temperature measurement problems above 500/sup 0/C, except in a few instances where problems at lower temperatures may affect the high temperature results. The upper limit of temperature measurement problems discussed is 3000/sup 0/C, as this is the normal maximum use temperature of the techniques included in this review. Problems in applied temperature measurements, rather than in standards, are considered, and emphasis is placed on problems due to high temperature limitations of materials in the thermometer sensors. 199 references. (JGB)

An Infra-red Technique for the Measurement of Gear Tooth Surface Temperature

Work in the field of gear tooth surface distress during recent years has shown clearly that surface temperature history provides the key to performance predictions. This especially applies when using an EP oil. Many attempts have been made to monitor surface temperature by using a variety of thermocouple designs. None of these attempts has resulted in the developing of a practical tool and all interfere with the surface continuity and can initiate scoring. An infra-red technique offered a satisfactory solution to this temperature measurement problem if the complexities of calibration could be resolved. This paper describes how a satisfactory technique was evolved along with results of proving tests when applied to a spiral bevel pair. Also included is the surface temperature history of a score/recovery mechanism. A practical tool for the measurement of gear tooth surface temperature has been developed and, slightly modified, the same technique is now being applied to temperature measurements within a roll...

The absolute thermopower of some low temperature thermocouple wires in high transverse magnetic fields

The thermopowers of some low temperature thermocouple wires have been measured from 4.2 to 100 K in magnetic fields up to 100 kG. Our technique is designed to circumvent the usual problems of temperature measurement in high magnetic fields. Some representative curves which display the absolute thermopowers of Au–0.07 at.%Fe, Chromel P, and ``Silver Normal'' in a transverse magnetic field are presented. A complete set of calibration tables for thermocouples of type Chromel P vs Au–0.07 at.%Fe and type ``Silver Normal'' vs Au–0.07 at.%Fe have been prepared and are available upon request.

Temperature measurement in shock-heated gases

This paper describes the techniques being adopted in the measurement of absolute line intensities for neutral atoms of iron, lead, and tin. Particular attention is paid to the problem of temperature measurement in the shock tube, and a method is described which gives satisfactory results in the range 4000–6000°K.

High Temperature, Small Diameter, Radial Heat Flow Thermal Conductivity Apparatus

A high temperature thermal conductivity apparatus has been designed and built. The apparatus employs a cylindrical geometry and radial heat flow and is accurate to ±5%. The thermal conductivities of germanium and silicon from 300°K to their respective melting points were measured with this apparatus. The special problems of high temperature measurements encountered with the apparatus are reviewed and discussed. In solving the high temperature measurement problems the eutectic temperatures of two germanium alloys (on the germaniumrich side of the phase diagram) were measured to about ±3°C. These are 909°C for germanium-iridium, and 932°C for germanium-tantalum. Germanium and molybdenum did not react noticeably.

A high temperature attachment for an X-ray diffractometer for precision lattice parameter measurements

A description is given of the design, construction and use of an attachment for an X-ray diffractometer which enables lattice parameters to be determined to 1 part in 20 000 at temperatures between room temperature and 1000°C. Special attention is given to the problems of temperature measurement and uniformity. The instrument also incorporates a device for specimen alignment. The results of a study of the thermal expansion of pure aluminium are given and are found to be in excellent agreement with the recent single crystal results of Simmons and Balluffi.

The Relationship between O18/O16 Ratios in Coexisting Quartz, Carbonate, and Iron Oxides from Various Geological Deposits

Analytical techniques for the extraction of oxygen for oxygen isotope analyses involving the high-temperature reduction of minerals with carbon are described. These techniques give reliable results for a few important minerals, including quartz and iron oxides, but give unreliable results for most silicates. Oxygen isotope analyses have been made on naturally occurring and genetically associated carbonates, quartz, and iron oxides. The relationships between the oxygen isotope compositions of the coexisting minerals are consistent with those reasonably expected from known thermodynamic considerations of isotopic fractionation. Relative temperatures inferred from the isotopic data are in excellent agreement with those estimated from other geological evidence. The implications of the oxygen isotope data on the problems of temperature measurements, on the presence or absence of chemical equilibrium between mineral phases, and on the study of isotopic compositions and relative amounts of hydrothermal waters in contact with the minerals are discussed.

A SPECTROPHOTOMETRIC DETERMINATION OF EXHAUST GAS TEMPERATURES IN THE PULSE-JET ENGINE

This paper describes a spectrophotometric method whereby instantaneous values of a variable flame temperature, in the particular case of nonluminous flames, may be determined and continuously recorded.This new technique, which depends upon the establishment of monochromatic black-body radiation conditions in the flame for a small region in the visible spectrum, involves the continuous measurement of radiation intensity in the above region, the intensity being, thereafter, correlated with the temperature of the flame.The problem of temperature measurement in the general case of nonluminous flames (flames which do not contain an appreciable amount of free carbon in the form of soot) is considered and a brief review of previous techniques employed for this purpose over the past 50 years is given. The basic theory and preliminary experimental justification of the present method are discussed.A description of the apparatus and the experimental arrangement used by the author in a specific application of the present method in the determination of the time variation of temperature in the exhaust flame of a pulse-jet engine is given. This includes details of a special type of spectrophotometer which employs a multiplier photocell as the radiation detecting and measuring element and, also, a "black-body" cavity constructed as a standard radiation source for the calibration of the former instrument. An original technique used to investigate the emissivity of flames colored by alkali metal vapors is described and its application to the present problem shown.Finally, the measurable temperature range of the present apparatus is considered together with the inherent limitations of the new method.