摘要:

This adiabatic solution calorimeter was designed specifically for thermochemical studies of the less familiar oxidation states of the rare earths. It has been used in the determination of the heats of solution of Pr, Eu, EuCl2, and Pr(NO3)3in acids. Currently, it is being employed in the determination of the heats of formation of the various stable, nonstoichiometric oxides of Pr. Close control of adiabatic conditions is maintained automatically throughout a run; manual manipulations are held to a minimum. The calorimeter holds about 200 ml of acid or water into which a solid sample is dissolved at the appropriate time. The temperature of the adiabatic shield which surrounds the calorimeter automatically increases at nearly the same rate as that of the calorimeter itself, and the increment of temperature is measured with a platinum resistance thermometer. The heat generated by a chemical reaction is calculated from a comparison of this rise in temperature to that caused by a calibrated quantity of electrical heat. Included in this paper are (1) a complete description of the apparatus, including figures; (2) a table giving results of some calorimetric experiments; and (3) a summary of the characteristics of the calorimeter.

ISSN:0034-6748    

DOI:10.1063/1.1683969

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The use of a multichannel scaler to improve the signal‐to‐noise ratio of current waveforms obtained from drift tubes is described. Using this technique very rapid improvement in the signal‐to‐noise ratio can be achieved which allows unstable gases to be readily studied.

ISSN:0034-6748    

DOI:10.1063/1.1683970

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

By varying the length of a constant area passage in which the mass flow is limited by frictional effects a controllable valve results with characteristics close to those of the critical flow orifice. This design principle leads to a simple valve geometry which is easier to manufacture and is generally sturdier than a comparable needle valve. For a prototype and a bank of 10 similar valves designed to furnish 0.025 kg/sec from a 10 MN/m2source of air, the results confirm fine control of the mass flow rate by a factor of 2 or more and a mass flow rate dependent on the square root of upstream stagnation pressure.

ISSN:0034-6748    

DOI:10.1063/1.1683971

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A low level dc detection system with an attainable precision of 25 pV is described. The system uses only normal metal components and commercially available equipment. Measurements can be made automatically, in the presence of large (microvolt) spurious voltages, with switched inputs, and in a non ``null'' configuration. A typical application is described in detail.

ISSN:0034-6748    

DOI:10.1063/1.1683972

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A compact data transmission system for crossing a high voltage interface has been built and tested. The system employs an infrared, incoherent light emitting diode and a silicon photodiode detector to telemeter the pulse width modulated signals. Departure from linearity was observed to be 2.7% rms. The frequency response was 3 dB down at 10 kHz.

ISSN:0034-6748    

DOI:10.1063/1.1683973

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

After reviewing the present state of knowledge concerning the technique of making high power sinusoidal pulses, an improved kind of line generator is proposed. An analysis of wave propagation in a periodic structure together with the numerical solution of the network differential equations shows that it is possible to utilize the recurrent triggering system (hitherto applied only to homogeneous lines) with lumped element lines. A method for designing such lines is presented. Numerical tables are included and some selected examples are discussed. The theory agrees with an experiment made with a prototype line. The construction of a 720 MW, 3 MHz installation for use in plasma physics experiments is already underway. This large power is achieved by paralleling a number of lumped element line generators.

ISSN:0034-6748    

DOI:10.1063/1.1683974

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A very simple and highly sensitive ``hot wire'' type level detector to be used with cryogenic liquids is described. The hot filament is made of tungsten wire of about 4 &mgr; diam. The tests on the sensor were made moving the filament in and out of the quiescent surfaces of liquid helium and nitrogen. The results showed 0.006 mm sensitivity in the determination of liquid helium level and 0.002 mm sensitivity in the case of liquid nitrogen level. The sensor is assembled in such a way that it can be used without special precautions during indefinite periods of time. For the case when the full capabilities of the sensor are not necessary, a simple circuit is presented.

ISSN:0034-6748    

DOI:10.1063/1.1683975

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A photogrammetric system is described which was developed to measure the three‐dimensional coordinates of a matrix of 100 &mgr; diam markers identifying a surface whose topography changes with time. The distance between any two markers whose centers are more than 300 &mgr; apart can be determined with a standard error of 34 &mgr;. An application of this system to the determination of cardiac muscle dynamics is demonstrated.

ISSN:0034-6748    

DOI:10.1063/1.1683976

出版商:AIP    

年代:1969

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1683977

出版商:AIP    

年代:1969

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1683978

出版商:AIP    

年代:1969

数据来源: AIP