Mass Measurement System Research Articles

Development of a Mass Measurement System with an Active Dynamic Vibration Absorber.

Development of a Mass Measurement System with an Active Dynamic Vibration Absorber.

Mass-measurement under weightless conditions by the frequency-controlled method

In this paper, we propose an accurate mass-measurement method under weightless conditions that is termed the “frequency-controlled method (FCM)”. Under weightless conditions such as in space-based laboratories, it is impracticable to use the mass-measurement systems we conventionally use on earth, because they make use of gravity. The gravity in a space laboratory is said to be only 1 10000 to 1 1000 times as much as that on the earth. Therefore, the establishment of mass-measurement methods under weightless conditions is indispensable for space development. In the following, we explain the principle of FCM, and show that FCM is an accurate and more desirable mass-measurement method under weightless conditions through the results of the experiment.

動吸振器を利用した無重力環境下での質量測定

A new type of mass-measurement system under weightless conditions is proposed which uses a dynamic vibration absorber as a measuring device. In this system, an object to be measured is fixed to a rotating table (rotor) at a distance from the rotation axis. Since it makes the rotor unbalanced, a centrifugal force whose amplitude is proportional to the mass is generated during rotation. It works as a harmonic excitation and forces a structure supporting the table to vibrate. However, a dynamic vibration absorber attached to the structure is tuned or controlled to reduce the vibration to zero. When the structure does not move at all, the absorber mass vibrates in such a way that the product of the mass and the displacement amplitude is equal to the amount of unbalance, that is, the product of the mass to be measured and its distance from the rotation axis. Therefore, the mass of the object is determined by measuring the displacement amplitude of the absorber mass. In this study, the principles and features of the proposed mass-measurement system are clarified. Experiments are carried out with a developed apparatus having an active dynamic vibration absorber. This apparatus can perform measurement at various rotational speeds because the absorber’s natural frequency can be tuned by a feedback parameter. Experimental results demonstrate the feasibility of the proposed mass-measurement system.

A CBNM isotopic reference material set for testing linearity of isotope mass spectrometers (CBNM IRM 072/1-15)

Any mass spectrometric measurement system has inherent inaccuracies caused by isotope fractionation in the ion source and non-linearity of the detector and or measurement system. A set of well known triple isotope mixtures is an excellent means to verify and correct non-linearity of the mass spectrometer detector and measurement system after the isotope fractionation has been corrected for. CBNM IRM 072/1-15 is a set of such mixtures. Its preparation and characterization is described. It is available for interested users.

Direct mass measurements at the TASCC facility: The Manitoba-Chalk River on-line mass spectrometer

The Chalk River On-line Isotope Separator has been used by itself to determine the masses of unstable nuclei. The addition of a high-resolution mass spectrometer for the further analysis of beams from the separator, currently on-line at the TASCC facility at Chalk River, offers an improvement in the accuracy and sensitivity of the mass measurement system. The characteristics and projected performance of the proposed apparatus are described.

速度・変位検出形質量動的測定システムのソフトウェア

速度・変位検出形質量動的測定システムのソフトウェア

Metering of High-Vapor-Pressure Crude Oils: The Case for Mass Measurement in Shared Pipeline Systems

Summary The paper discusses the relative merits of mass vs. volumetric measurement as the basis for equitable allocation of high-vapor-pressure (HVP) crude oils commingled in shared pipeline systems. Measurement uncertainties for both methods are compared. The problems of continuous density measurement and of automatic problems of continuous density measurement and of automatic sampling for composition analysis and water content determination are discussed. Introduction Capital and running cost economics make it commercially sensible to transport crude oil in shared pipelines. This practice is employed widely in North Sea operations. practice is employed widely in North Sea operations. where crude oil from several different fields or licensed areas may be gathered into a single pipeline for transfer to a land-based terminal. The compositions of the field crudes commingled in the pipeline may differ, with each containing varying proportions of reinjected-natural gas liquid (NGL) condensate and other light hydrocarbons. These light components are recovered from the cocktail of total received crude at the onshore receiving terminal, with the propane and butane re-exported as individual products, separate from the main bulk of the commingled products, separate from the main bulk of the commingled stabilized crude. Some dissolved gases also may be sold separately or used locally as fuel. The method used to measure each offshore subscription to the pipeline and the total cocktail received at the terminal must allow for accurate and equitable pro rate allocations to participants on the basis of their contributions to the total of each marketed component. Legislative requirements for the measurement of oil won and saved also must be satisfied. This paper discusses the alternative principles of measurement and examines the factors that principles of measurement and examines the factors that influence the measuring, uncertainties in each case. On the new BP Intl. Ltd. Magnus Platform, measurement is made of the total mass of live crude exported into the Ninian shared pipeline system. The Magnus metering system is described briefly to illustrate the application of a practical high-vapor-pressure (HVP) crude mass measurement system. Measurement Principles The allocation of a shared crude oil pipeline throughput may be based on two basic measurement principles. These are volume and mass. Allocation by Volume The arguments for using volume as a basis for allocation are primarily commercial rather than technical.Crude oil is sold by volume. It is the traditional basis for international oil trading. The standard international commercial unit is the U.S. barrel, although for European fiscal accounting, the unit is the cubic meter. Both are oil volumes measured at reference conditions of temperature and pressure (barrels at 60 deg.F, 14.7 psia [cubic meters at 15 deg.C, 101.325 kPa]). The trading basis for liquefied petroleum gas (LPG) is by weight.There is significantly less variation in the value of crude oil when the oil density changes if the value is defined in dollars per barrel rather than dollars per tonne. Generally. low-gravity (light) crudes are intrinsically more valuable than heavy crudes.Pipeline fill figures and storage tank capacities are essentially volumetric. For stock computations and system control, both pipeline and terminal operators require reports of movement in volumetric terms.Allocation by volume requires only volumemetering, with supplementary measurement of temperature and pressure; the techniques and equipment for these pressure; the techniques and equipment for these measurements are reliable and well established. Volumetric allocation also avoids the need for on-line density measurement since, except for qualitative valuation, density is not a first-order factor in the calculations. The practical and commercial advantages of volumetric allocation are offset by a number of factors that may affect the accuracy of the measurement. These may arise particularly from such parameters as the shrinkage effect particularly from such parameters as the shrinkage effect (nonideal mixing) and volume variations with temperature and pressure. The uncertainties of these factors are particularly acute in the case of crude oil containing particularly acute in the case of crude oil containing significant proportions of light-end components. Such factors do not apply in the alternative case-allocation by mass. Allocation by Mass Allocation on the basis of mass is now the most widely practiced procedure in North Sea shared pipeline systems. The reasons are related largely to fundamental physical principles. However, the commercial/trading considerations also apply in the specific case of condensate because it is sold by weight. There are two principal arguments for allocation by mass rather than volume. 1. Mass is an inviolate property. Unlike volume, itremains unaffected by temperature and pressure. JPT P. 2002

質量・力計測システム調査研究分科会報告(分科会報告No.322,委員会報告)

質量・力計測システム調査研究分科会報告(分科会報告No.322,委員会報告)

Mass Measurement: A Study of Anomalies

It has always been assumed that the measurement of the difference in mass between two objects would be the same in all laboratories. Recent National Bureau of Standards measurements involving dissimilar objects (effective density ranging from 2.7 to 16.6 grams per cubic centimeter) at a wide variety of pressures (0.5 to 2 atmospheres) have been made with sufficient precision to test this assumption. The results show unsuspected discrepancies which may approach 1 milligram in a kilogram in the assignment of mass values when dissimilar materials are involved. These discrepancies have not been noted in the past because precision comparisons of both like and unlike materials have nearly always been made in a relatively restricted range of environmental conditions. The worldwide mass measurement system is therefore consistent, because similar materials have been used in the construction of weight sets, but possibly offset with respect to the mass unit as embodied in the platinum-iridium defining artifact.