The Instrumented Indentation Test is based on simultaneous recording of force and indentation depth, obtained during test cycle. The force-depth curve, describing the indentation pattern, is typically formed by two parts having the “zero-point” in common, i.e. the first contact point between the indenter and the surface of test piece. The zero-point determination is a crucial aspect for Martens Hardness evaluation, so that relevant ISO standard suggests to estimate it by extrapolation of polynomial fitted functions. In this paper a new model, based on a segmented function, is proposed. This approach implies the use of maximum likelihood estimator for parameters determination. The corresponding uncertainty is provided through the covariance matrix of the regression model.

The paper describes the newly developed "NMi TraSys" - NMi Traceability System. This travelling carrier & multiplier of traceability has been realized to embody a significant part of the Dutch National traceability-chain for high-pressure gas-flow measurements. The number of contributions of uncertainty as well as their values, due to "copy-losses" and "installation-effects" during the traditional transfer of traceability from one facility to another, are decreased.
First results are presented about observed repeatability and reproducibility, uncertainties and consistency checks. The device will include in time, reference values of three different independently realized primary standards (viz. DDD - Dynamic Displacement Device, GOPP – Gas-Oil Piston-Prover and NMi TraSys itself). With internal harmonization processes at NMi VSL with "input" reference values from the three other primary standards, viz. DDD-conventional, DDD-extended pressure level and GOPP, the aim of 0,1% uncertainty at 4.000 m³ / h and p = 60 bar is within reach. This will improve the uncertainty as well as the stability of the Dutch National reference values considerably.
NMi TraSys will be used as a set of Travelling Reference Meters, creating an efficient availability of stable and validated Harmonized Reference Values for high-pressure gas-flow.

This paper analyses the possibility to have a dedicated signaling channel for triggering load balancing mechanism based on relevant specific traffic parameters analysis (e.g. throughput, EIRP, Antenna Gain). Compared to classic algorithms, the signaling channel brings the advantage of distributed “effort” between Access Points and Controllers. Experiments were performed with Matlab and the results show the network performance enhancement in terms of Load and Throughput. The proposed signaling channel shows effectiveness of the load distribution enhancing also the network performance.

This paper addresses the generation of spectrally pure sinewaves by combining the feedback structure of a ΣΔ loop with digital cancellation of unwanted spectral components in the output signal. In particular, the non-linearities of the in-loop Digital to Analog Converter (DAC) are compensated by applying a digital pre-distortion to the DAC input, and the feedback architecture is used to enhance the performance of the all digital estimation and cancellation algorithm.

During the last decade more and more interest has been found in making low frequency vibration measurements. One area that has driven this is the earthquake studies, but here accuracy is not a focus point. However when we start to look at large structures like wind turbines, large aircrafts with 60 to 80 m wingspan, bridges and 400 to 500 m towers the accuracy becomes vital. These large structures have vibration modes in the range 0.3 to 1 Hz.
The method for Primary vibration calibration by laser interferometry using quadrature outputs described in ISO 16063-11 can be extended down to 0.1 Hz today thus giving the foundation for accurate measurements in the low frequency (LF) range.
It is however desirable to link these results that are obtained at very low vibration levels and frequencies to measurements at 0 Hz with constant acceleration of about 9.8 m/s².
This method is basically described in ISO 5347-5 (to be revised as ISO16063-16) but a detailed description of uncertainty budgets is not given.
Recently the Danish Primary Laboratory of Acoustics (DPLA) participated in the first international comparison covering the LF range of vibration, and in that context we decided to make a 0 Hz calibration with relatively simple means but exploiting the fact that the local Gravity today can be determined by an uncertainty of about 10^-8.
By using a transfer technique and without utilising the full potential we could make an uncertainty budget with an expanded uncertainty of about 0.04% on a servoaccelerometer calibration, where one of the main contributions turned out to be thermal drift.
The experience we got during this calibration and the uncertainty budget created will be presented.