摘要:

We have improved measurement of the current‐axis‐independent Josephson sampler. We use a new chopping detection circuit in the feedback system for sampling point control. Two channels of the sampling head are utilized to cancel drift in the time base. Drift is about 3 ps. We have measured the output of a short pulse generating circuit and obtained a transition duration of 15 ps.

ISSN:0034-6748    

DOI:10.1063/1.1137293

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

This paper describes an experimental system developed for the purpose of studying the distribution of electric field in lossy bodies. Ultimately, a map of the internal electric field intensity in a phantom model of the human body exposed in the near field of radio and microwave radiators is obtained. The field is sampled by a nonperturbing probe in a number of points under computer control using a system consisting of a microcomputer and a minicomputer. A description is given of the hardware and software components of the scanning system and the results of experimental evaluation of the performance of the system. For illustration the electric field distributions in simple configurations obtained experimentally are presented and compared with analytical results.

ISSN:0034-6748    

DOI:10.1063/1.1137294

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The present paper describes a loop tracer devised for ferroelectrics that can record hysteresis phenomena instantaneously. Digital technology has been applied to the conventional Sawyer–Tower circuit to provide a new system. Owing to its fast operation, it is easy to observe the loop of aged specimens without changing their electrical state, as well as to follow the depolarizing process dynamically when an ac voltage is applied.

ISSN:0034-6748    

DOI:10.1063/1.1137295

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A simple and rugged polythene shielded radiometer is described. The instrument measures the net hemispherical thermal infrared irradiance of the sky even during daylight hours, using white and black sensors to separate solar from long‐wave thermal radiation. A compensation radiometer used to calibrate our instrument is also described, the calibration procedure permits measurements of the hemispherical thermal infrared irradiance of the sky with an error of ∼5% during the night and of less than 10 W/m2during daylight hours.

ISSN:0034-6748    

DOI:10.1063/1.1137296

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A microcomputer‐controlled gravimetric adsorption apparatus was designed and constructed. Components and software of the system are described. A microcomputer is used to control the experiment and to acquire data. The system is capable of conducting a complete adsorption–desorption run for various adsorbate/adsorbent systems quite accurately and efficiently. Results of the sorption of water and nitrogen on oxide and hydroxide powders are presented to demonstrate the performance of the apparatus.

ISSN:0034-6748    

DOI:10.1063/1.1137297

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

An automated system is described for measuring internal friction and elastic moduli using sonic resonance techniques. This mirocomputer‐controlled device does phase angle analysis in addition to traditional decay and peak‐width internal friction measurement. The apparatus may be programmed to make measurements at any sequence of temperatures between room temperature and 1600 °C.

ISSN:0034-6748    

DOI:10.1063/1.1137298

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A computer controlled microchemical robot which carries out a series of chemical reaction steps in DNA sequence analysis of Maxam and Gilbert’s scheme is described. Within a 2‐h operation of this apparatus, one of the four types of solutions for G, A+C, C+T, or C analysis for a DNA restriction fragment is prepared and is ready for subsequent electrophoretic analysis. It is proven that the chemical robot operated by a computer command is capable of speedily accomplishing the fragmentation reaction for DNA sequencing with accuracy similar to that of a well‐trained technician.

ISSN:0034-6748    

DOI:10.1063/1.1137299

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A theoretically ideal and simple dead‐time correction system for analog ratemeters is presented. It is based on the use of a correction amplifier controlled by the durations of measured pulses and it allows pulses with varied and unknown durations. A possible application area is the concentration measurement of monodispersive (or limited size distributed) particles using single particle optical counters. Experimental measurements of aerosol particle concentrations with a single particle optical counter shows that a significant extension in the measurement range is achieved.

ISSN:0034-6748    

DOI:10.1063/1.1137266

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Velocity calibration of a Mo¨ssbauer spectrometer operating in a constant acceleration mode has been obtained with a Michelson interferometer using an (Al, Ga)As laser diode. The very small size of the laser diode makes it possible to construct a very compact optical system for velocity calibration.

ISSN:0034-6748    

DOI:10.1063/1.1137267

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A convenient thyristor‐driven triggering circuit for trigatron gaps has been developed. For simplicity, the electric power of the circuit is fed from the high‐voltage terminals of the gap through a voltage divider. This circuit could trigger the trigatron gap successfully over the voltage range from 8 to 30 kV.

ISSN:0034-6748    

DOI:10.1063/1.1137268

出版商:AIP    

年代:1983

数据来源: AIP