The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The Joule balance method to measure the Planck constant and redefine the Kilogram ultimately has been going on at the National Institute of Metrology of China (NIM) since 2007. The first prototype has been built to check the feasibility of the principle. In 2012, the relative uncertainty of the plank constant measurement result is at 10−5 level. Self-heating of the coils, swing of the coil, etc.,...
This paper presents a special portable apparatus for workpiece magnetism determination of joule balance at NIM. It could be used to evaluate easily the magnetic variation of mechanical parts before and after processing, quickly measuring weak magnetic properties of materials. The measuring process is simple without a customized sample. From the variation of a mutual inductance value in two different...
The load effect of the resistor should be paid great attention for the precise measurement. Here a high accurate resistance voltage divider (RVD) used to precisely measure the load effect of the resistor is provided. A self-calibrated standard resistor at 100Ω with zero load effect is employed as one arm of the bridge, and several stable resistors with the same temperature coefficient and structure...
A simple differential eddy current sensor for measuring small rotation angle is presented and experimentally investigated. The output signal is obtained from changing active areas of a rotatable copper plate with two legs inserted into gaps of a magnetic circuit. Test results show this kind of sensor has a resolution of 8µrad over the effective measurement range of ±7000µrad.
In the weighing phase of the Joule Balance, to get a high enough magnetic field and avoid the heating from the coil wound with normal enameled copper wire, a superconducting magnet is used as the fixed coil. The mutual inductance measurement between this superconducting coil and the movable coil of enamel copper wire should be measured precisely. A standard square-wave compensation method has been...
Till now, quantized Hall devices distributed by the BIPM are used in NIM's quantized Hall resistance standard. In this paper, we report the preliminary results of quantized Hall devices with GaAs-AlGaAs heterostructures fabricated by ourselves. The device is with AuGeNi contacts for reliability consideration, but the contacts are with relatively large resistances for layer contents and annealing condition...
Base on the developed DC controlled current source to simulate the DC component in the earth, experimental researches are made to study the effects of DC-bias to the power transformer. Experiment results show that the magnetizing currents of the power transformer are distorted badly with the increase of the injected direct current which is controlled by the software system under the Lab VIEW environment,...
In the paper, the DC controlled current source (DCCCS) is developed to simulate the DC component in the earth to study the ability of power transformer enduring the DC bias. The designed DC-bias experiment is applied to validate the effectiveness of the DCCCS. Experimental results show that the developed DCCCS works well and could provide the desirable and controlled direct current required by the...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.