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Sascha Mäuselein, Oliver Mack, Roman Schwartz
INVESTIGATIONS TO THE USE OF SINGLE-CRYSTALLINE SILICON AS MECHANICAL SPRING IN LOAD CELLS

This article presents investigation results to the use of single-crystalline silicon as mechanical spring in load cells. As a result of the crystalline structure a very high reproducibility of the material properties is expected. In addition the mechanical aftereffects of single-crystalline silicon are by the factor of 100 smaller than in metallic materials. Performed simulations using the finite element method consider anisotropic and brittle material behavior. It is shown that silicon as mechanical spring material in combination with sputtered metal strain gauges principally can be used for load cells and force sensors.

Martin Kollár, Linus Michaeli
DETERMINATION OF THE POWER SPECTRAL DENSITY IN CAPACITIVE DIGITAL ACCELEROMETERS USING THEORY OF LIMIT CYCLES

Mechanical noise due to Brownian motion, electronic noise introduced by the interface circuit due to thermal noise sources in the electronic devices and quantisation noise due to the analog to digital conversion process are the main three noise sources presented in a sigma-delta modulator (ΣΔM) type system applied to a micromachined accelerometer: Based on theory of limit cycles in nonlinear closed loop systems, the mathematical model and formulae for power spectral density calculation of a micromachined accelerometer will be derived in the paper. The theoretical considerations will be verified with the simulation results in MatlabSIMULINK.

Jochen Schneider, Lioba Stenner, Georg Wegener
INVESTIGATION OF THE INFLUENCE OF TRANSDUCER ELECTRONIC DATA SHEETS (TEDS) ON CALIBRATION RESULTS

The international standard IEEE 1451.4 is the basis for transducer electronic data sheets (TEDS), where information related to the transducer like serial number or nominal sensitivity is stored into a chip inside the transducer. For bridge type sensors, with a novel circuit (patent pending) it is possible to read the TEDS information for 6-wire bridge sensors without additional wires by using the sense lines. The paper shows the investigations of the influence of TEDS on measurement results. Voltage ratio calibrations with TEDS between measuring amplifier and calibration unit had been carried out at different carrier frequencies. Verification measurements with the TEDS chip built into a force transducer checked for the technical specifications e.g. temperature behavior of the nominal sensitivity. Additional investigations focus on different linearization methods checked with force and voltage ratio calibrations. With force calibration according to ISO 376 a 3rd degree polynomial equation is calculated from the calibration results. With a new kind of amplifier it is possible to store the coefficients of this polynomial equation and make an online calculation. The results of the measurements when using TEDS to store the coefficients and read into the amplifier are presented.

David Kimetto
THE USE OF STRAIN GAUGES IN THE KENYAN INDUSTRY FOR MEASUREMENT

The rapid development of micro-electronics has produced an increasing demand for small sensors offering high quality performance. Strain gauges are an important aid in all areas of experimental stress analysis, for determining the strain on the surface of components. In addition, the uses of strain gauges in the manufacture of transducers for measuring mechanical quantities has proven to be extremely reliable technology, giving excellent results.

Dan-Mihai Stefanescu
N-SHAPED AXISYMMETRIC ELASTIC ELEMENTS FOR STRAIN GAUGED FORCE TRANSDUCERS

Only few types of flexible structures are recommended for measuring very large forces. The axisymmetrical ones are best suited in this respect, their maximum strain gauge (tensometrical) sensitivity being ensured in bending. The force transducer body is easy to design by 2D finite element method (FEM) and easy to manufacture. Numerical investigations on various models of N-shaped strain gauged elastic elements are presented together with their advantages in the field of force measurements.

C. Ferrero, C. Marinari, R. Kumme, W. Herte
PTB AND INRIM HIGH FORCE INTERCOMPARISON UP TO 9 MN

The present paper describes the long term stability of the main metrological characteristics of the two reference transducers of 3 MN and 9 MN together with the relevant uncertainties evaluated from the measurements carried out by INRIM and PTB by bilateral comparisons. In June 2004, the new INRIM – 3 MN build-up system (BU), the 9 MN and 5 MN transducers were also intercompared, by using the PTB 2 MN DWM and the 16.5 MN Hydraulic Multiplication Machines (HMM). The main results are reported. Furthermore long term investigations carried out over 20 years and the work obtained within a EUROMET project are described.

A Knott, A Abu-Elezz, M Ibrahim, E Hasan, G Aggag
COMPARISON OF FORCE STANDARDS BETWEEN NIS (EGYPT) AND NPL (UNITED KINGDOM)

This paper details the results of a bilateral comparison carried out between the national force standard machines of Egypt and the United Kingdom. The results indicate that the uncertainty claims of the two laboratories can, in general, be supported. Recommendations on revised protocols to be used for future comparisons are given.

Janusz Pienkowski
DIODE LASER FREQUENCY STANDARD FOR LASER INTERFEROMETRY

Diode lasers are becoming increasingly important in length metrology. We demonstrate construction of a simple single-frequency diode laser 632,8 nm, used as a frequency standard in the laser interferometers. We present two different systems applied for frequency stabilization of diode laser . For diode laser used as the secondary standard, the system stabilizes diode temperature, the frequency stability of the laser reaches value 1 part in 106. For diode laser used as the primary standard is developed stabilization system using narrow absorption in iodine , the frequency stability of constructed diode laser reaches value 1 part in 1010.

M. Yoshida, I. Ishimaru, K. Ishizaki, Y. Inoue, T. Yasokawa
TRANSLATIONAL VELOCITY MEASUREMENT FOR TRACKING OF SINGLE FLOATING CELLS

We propose the optical spatial filtering method, as translational velocity measurement to observe morphological changes of single floating cells in long stretches. This measurement derives the arbitrary component of the spatial frequency from the random refracted index distribution as the periodic light intensity distribution.

Hideo Furuhashi, Yoshiyuki Uchida, Kiyofumi Matsuda, Akihiro Kono
OPTICAL DIFFERENTIATION PHASE MEASUREMENT USING A MODIFIED MULTI-STEP BIAS-SHIFTING METHOD

An optical differentiation phase measurement system using a modified multi-step bias-shifting method is proposed. The signal obtained by multi-step bias shifting is divided into two groups in this new method. The effectiveness of the new method was demonstrated using a computer simulation.

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