摘要:

Rates of flow of gases may be measured to an accuracy of better than 0.1 percent with properly modified and operated wet test meters. The period of a single rotation is measured by an electric stop clock. The instrument is not an absolute one but must be calibrated by a meter prover. A suitable prover is described. Within rather wide limits the calibration is independent of flow rate. The instrument may be used for direct measurement or for calibrating other types of flow meters.

ISSN:0034-6748    

DOI:10.1063/1.1745690

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

Kirchhoff's law equations may be written for any electrical network. Conversely, it is usually possible to find an electrical network whose Kirchhoff law equations are similar to the given set of simultaneous equations. The solution to the equations may then be found by measuring the corresponding quantities in this analogous network. The a.c. network calculator is adaptable to this method of solving equations. Presented here are the fundamentals of finding the correct electrical network for a given set of simultaneous equations.

ISSN:0034-6748    

DOI:10.1063/1.1745691

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

The application of binary arithmetic in the computing circuits of a high speed digital computer is discussed in detail. The discussion covers, with numerous examples, the use of complements to represent negative numbers, the corrections necessary in the multiplication process as a result of the use of complements, and additional modifications of the process to simplify mechanization. A special division method well‐adapted to automatic computer use is described, and round‐off procedures are noted briefly. The article is concluded with a discussion of the storage of negative numbers as absolute values with a sign rather than in complement form.

ISSN:0034-6748    

DOI:10.1063/1.1745692

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

A recording polarimeter has been constructed. The principle of operation is essentially the replacement of an operator in conventional visual polarimetry by a photoelectric servo system. A photo‐multiplier tube is used which, in conjunction with a mechanical chopping system, delivers an alternating current signal proportional to the unbalance. The latter is filtered and amplified and actuates a servo mechanism. The precision of the system is ±0.005° for static balance and the speed about 0.5° per minute. Hence the arrangement compares favorably with ordinary visual operation. The construction of the instrument is discussed briefly and its performance is illustrated by examples.

ISSN:0034-6748    

DOI:10.1063/1.1745693

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

Certain new developments in ionization chamber technique are described. Ionization chamber counters have been designed to operate with fillings of H2, D2, or CH4to pressures of 35 atoms. with simple filling techniques. The design, characteristics, and uses of these counters are described.

ISSN:0034-6748    

DOI:10.1063/1.1745694

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

A single crystal neutron spectrometer has been constructed which shows improvement in resolution and intensity over previously described instruments. This has been made possible by the high flux available from the Chalk River heavy water reactor. The instrument can be operated automatically.Mechanical design, crystals, resolution and the contamination of the spectrum by higher orders are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1745695

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

The paths of electrons in a thin magnetic‐lens type of spectrometer are described by a non‐linear differential equation. The equation was numerically integrated to obtain a set of electron trajectories originating from a point source on the axis of the instrument. Trajectories for off‐axis sources were approximated. On the basis of these trajectories, the location and some properties of ring focus were studied. Theoretically calculated line shapes are compared for axial and ring focus. For reasonable values of resolution, the transmission of the spectrometer would be roughly doubled by performing the momentum discrimination by a ring focus baffle instead of by a small counter on the axis.

ISSN:0034-6748    

DOI:10.1063/1.1745696

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

Testing lenses, particularly photographic lenses, in a simple, fast, and accurate manner is quite a difficult problem. One of the solutions to this problem is a lens tester which is basically a modified autocollimator with a built‐in color filter arranged in conjunction with an assembly unit consisting of an adjustable microscreen and a lens holder. This latter unit may be rotated about an axis perpendicular to the optical axis of the instrument, giving an immediate reading of the tangential and sagittal foci. By means of this instrument it is possible to determine: (1) the flange focal distance, (2) the shift of axial focus with respect to the lens aperture, (3) longitudinal chromatic aberration, (4) tangential and sagittal foci for any angular distance from the axis and for any aperture, and (5) all these readings for various color bands. This new instrument makes possible the immediate reading of the results without further computation. The determination of the nodal point and the focal length for extra‐axial aberrations is unnecessary. Built‐in color filters allow testing for chromatic aberrations. Because of a special microscreen and reflection‐free beam splitter arrangement, this instrument gives satisfactory readings also for small apertures.

ISSN:0034-6748    

DOI:10.1063/1.1745697

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

A Nier‐type mass spectrometer and its associated electronic units have been constructed for the purpose of measuring small variations in the abundances of oxygen of mass 18 and of carbon of mass 13 in carbon dioxide, and of oxygen of mass 18 in oxygen gas, to an accuracy of ±0.01 percent of the abundance of these isotopes.The electronic units of the necessary stability for this degree of accuracy are described. A gas feed system is described which permits fast alternate introduction of the sample of gas to be analyzed and a standard gas into the mass spectrometer. All measurements of the variation in the abundance of the oxygen and carbon isotopes are made with reference to a standard.

ISSN:0034-6748    

DOI:10.1063/1.1745698

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

Rubber, Teflon, and vinyl acetate sealed systems are compared, by an approximately quantitative method, with a lead gasket sealed system which is shown to give off negligible gas at room temperature. Rubber is shown to evolve relatively large amounts of gas with an apparent vapor pressure above a micron at room temperature and about 0.1 micron at liquid air temperature. Continuous pumping for several days produces no improvement, nor does the use of metal‐to‐metal joints. Vinyl acetate joints are shown to improve with pumping over a period of several days, reaching a condition exhibiting an ``apparent vapor pressure'' of 5×10−7mm of mercury, or less, at room temperature. Heating to 45°C raises the apparent vapor pressure to the 10−5mm range, and heating to 100° raises the apparent vapor pressure to the micron range. If this behavior is caused by the vapor pressure of the vinyl acetate itself, continued baking in vacuum will, of course, produce no improvement.

ISSN:0034-6748    

DOI:10.1063/1.1745699

出版商:AIP    

年代:1950

数据来源: AIP