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The response time of flow-diversion valve controls currently available is about 5 seconds when the sensing element is immersed in water, and can be as much as 15 seconds in viscous milk products. Control systems with faster response times are needed for both ultra high-temperature and high-temperature, short-time systems. The temperature sensing element is the slowest component of the control system, and because of this, the speed of response of a thermocouple, thermistor, and resistance bulb was compared with that of the vapor-filled bulb currently used. Measurements were made in a 7.6-cm-diameter tube, with initial and final milk temperatures of 78.3 and 67.8C. Sixty-three per cent of the down-scale step change (the thermometric lag) occurred at diversion temperature of 71.7C. With a milk velocity of 2.4 meters per second, thermometric lags of the thermocouple, vapor-filled bulb, thermistor, and resistance bulb were 0.34, 1.5, 2.0, and 2.4 seconds. With a milk velocity of 0.3 meters per second, thermometric lags were 0.86, 3.1, 3.0, and 3.6 seconds. The thermocouple was the only sensing element tested with the potential for significantly decreasing response time of flow-diversion valve control systems.

SUMMARY 1. Desert iguanas exercise control over their body temperature by appropriate adjustment of their position in artificial and natural thermal gradients. 2. The preferred level of body tem- perature, which is defined as the median of the body-temperature distribution, is 38.5 C. 3. Thermoregulation in desert iguanas is fairly precise with the central 50, 68, and 95% of the body temperatures rang- ing between 37.0-39.5, 36.1-40.1, and 33.2-41.8 C, respectively. 4. The body-temperature distribution for desert iguanas is negatively skewed. This may reflect a characteristic of the system for temperature sensing employed by lizards. In analysis of body-tempera- ture preferences, neither the usual as- sumption of normality nor the common practice of casting off records of low body temperatures is wholly justified. 5. Under certain experimental condi- tions, temperatures of the head and trunk may differ by several degrees; but under natural conditions, these tempera- tures do not differ by more than a degree. 6. Under desert conditions during summer, desert iguanas prolong their activity period by permitting body tem- peratures to rise above the preferred level to 42 C and higher. 7. Body temperatures are permitted to rise well above the preferred level during territorial fighting behavior and in the presence of predators but generally are not permitted to do this during feed- ing and courtship.

A modified temperature sensing circuit for the Phillipson microbomb calorimeter allowed accurate calorific determinations on samples as small as 3 cal.Calorific values of copepods from three lakes in eastern Ontario varied with species, developmental stage, lake, season, and year. No such differences were observed in calorific values for the few species of rotifers and cladocerans tested.Similar calorific values were obtained for samples preserved by freezing, freeze-drying, and heat-drying, but preservation in formalin resulted in erroneously low calorific values.

The solid acoustic thermometer is basically a remote acoustic resonator for temperature sensing. It can employ any of a large number of materials, giving a freedom of choice not possessed by other methods of temperature measurement. The instrument is being evaluated in systems where thermocouples and pyrometers have proved unsatisfactory.

A precision thermostat is described which has a relative RMS temperature constancy of ±.10 m°C over a week. Maximum temperature deviation from mean temperature during one week is typically ±.2m°C. The distribution of temperature along the middle axis of the thermostat is almost linearly increasing with height with a mean gradient of +.05 m°C/cm. We further investigated the stability of NTC resistances as temperature sensing elements.

Careful consideration of the heat transfer equations for a rocket-borne stratospheric temperature sensor in the form of a spherical bead thermistor coupled with an experimental analysis of the physical, thermodynamic and electrical characteristics of the rocketsonde, indicated that the corrections to the observed thermistor temperatures could be substantially reduced through development of a new rocketsonde. Redesign of the rocketsonde temperature sensor reduced the theoretical temperature correction at 65 km from a value of 36C for the Delta-I temperature sensing instrument to approximately 6C for the new design. Temperature data obtained with the new stratospheric temperature sonde STS-1 showed that, after instrument expulsion at 74 km and at rocket nose-cone temperature near 100C, the thermistor temperatures at and below 60 km were, without correction, in close agreement with those predicted by the U. S. 1962 Standard Atmosphere.

An apparatus for extending the steady state freezing point depression method to small volumes, of the order of 0.3 or 0.4 ml, has been developed. A thermistor is used as the temperature sensing element, in one arm of a Wheatstone bridge. The apparatus is simple and dependable. Accuracies in the order of 2% are easily attainable.

A comparative study is made of various rocket instrumentation and sensing techniques for collecting stratospheric wind and temperature data. The rocketsondes employed in synoptic studies in general use the spherical bead thermistor as the temperature sensing element. Different designs of sensors were launched in close proximity, and results agree within 3C. Different parachute configurations and chaff are compared for their ability to sense winds. In most cases, wind velocities agree within reason (5 m sec−1) among the different types of sensors. The major corrections that are applied to wind and temperature data are discussed. The corrections are small (less than 2° and 10 mps) below 50 km but increase with height and in some extreme cases can reach values of 200 m sec−1 for winds and 11C for temperatures at 60–65 km.

Animal temperature sensing for studying effect of prolonged orbital flight on circadian rhythms of pocket mice

To determine the temperature response of the brain to radiation, thermistor temperature sensing probes were implanted into thalamic and cortical areas of eight monkeys and the arch of the aorta. After securing base-line temperature recordings, the monkeys were exposed to 2500 rads whole-body pulsed mixed gamma-neutron radiation in the AFRRI-TRIGA reactor. Temperature at all measured sites generally dropped briefly immediately after the pulse, then rose and stayed elevated 1-2C for the remainder of the 3-1/2-hour observation period. There did not appear to be any regional differences in brain temperature response, and brain temperature followed core (aortic) temperature changes.

Calorimeters applicable for the measurement of thermodynamic parameters by the continuous titration technique have existed for about fifteen years. During this time, problems associated with the components of the calorimeter (i.e. constant temperature bath, constant rate buret, reaction vessel, temperature sensing circuit, and data analysis procedure) have gradually been solved so that the continuous titration method now gives results comparable in accuracy to those obtained in conventional solution calorimeters. Inexpensive research quality titration calorimeters have become available commercially in the last few years.

A voltage stabilizer has been integrated in one crystal with a thermostat for a very low temperature coefficient. Temperature sensing systems, temperature sensors without drift and the influence of the thermal resistance of the encapsulation, will be described.

The past fifteen years have witnessed the development of reaction calorimetry as an analytical methodology. The applicability of such techniques as thermometric enthalpy titration (TET) (1) and direct injection enthalpimetry (DIE) (2) to clinical and biochemical problems has greatly enhanced this development. All of the above mentioned techniques most commonly utilize a thermistor as the temperature sensing element. It is well known that thermistors are among the most sensitive and simple temperature transducers available. The detection limit of these devices is controversial. Recently Lampugnani and Meites (3) have reported an 0.6 µ° C limit, while Smith, Barnes, and Carr (4) and Dohner, Wachter and Simon (5) have reported a value of 3.5 (µ° C. Considerably higher values have also been reported (6). Thus an investigation was initiated into the effect of various physical factors which might influence thermistor sensitivity.

The PLSS schematic with the water boiler option is depicted in Fig. 3 and is the same as the flash evaporator system except that the flash evaporator subsystem is replaced with an integral wick-fed water boiler. The sink temperature is controlled by the back pressure control valve which is a temperature sensing device. Notice that full flow of the liquid heat transport loop through the boiler is maintained to allow for cooling of the O2 ventilation loop during umbilical operation. The PLSS schematic with the water sublimator option is depicted in Fig. 4 and is the same as the flash evaporator system except that the flash evaporator subsystem is replaced with the water sublimator subsystem. The water reservoir (item 16) is pressurized to 8.0 psia by the O2 ventilation loop and acts as the accumulator for the liquid heat transport loop as well as supplying expendable water to the sublimator. Again, full flow through the sublimator is maintained to allow for cooling of the O2 ventilation loop during umbilical operation.

The advantages of using a combination of semiconductor diodes and carbon resistors as temperature sensing elements in the liquid nitrogen range is shown and an automatic filling system for liquid nitrogen is described.

A practical infrared sensing apparatus has been developed to profile the temperature distribution of small complex structures without affecting the temperature distribution by the temperature sensing element. The sensitivity is 60°C for some materials, and the resolution is 1.3 mils.

The potential of using neutron transmission as a temperature sensor is demonstrated.

The rate at which a temperature-sensing element located in the gas stream of a jet engine responds to sudden changes in temperature is of great practical importance in the control and operation of such an engine. The factors that determine rate of response are discussed, and the significance of the characteristic time is emphasized. It is shown that laboratory determinations of characteristic time must be made under simulated engine conditions in which the rate of heat transfer by forced convection is the controlling factor. Apparatus used at the National Bureau of Standards for measuring characteristic times is described, and typical results are presented. The rate of response of a device in a jet engine varies greatly with engine speed and with the altitude of flight, so that satisfactory performance of a temperature-actuated control system can be expected only if the sensing element responds with sufficient rapidity under starting conditions and at the flight ceiling.