Knowledge of the transfer function of a force transducer is required in order to determine a transient force from the transducer's output signal. We describe a linear least-squares fit method for system identification to estimate the transfer function from sinusoidal force calibration measurements, and we consider the evaluation of uncertainty associated with the obtained estimate. In applying this method to different calibration measurements it is demonstrated that consistent results are obtained for the transfer function.

The most important principles, the basis and operation of heterodyne and homodyne interferometers are discussed. Their benefits and limitations are covered based on a metrological analysis. The resolution of interferometers can be determined by calculating the smallest resolvable distance increment. Also, it is shown here how the Abbe comparator principle can be fulfilled in all three measuring dimensions by using interferometers. Other factors in addition to the Abbe errors are discussed which affect the measurement uncertainty of interferometric length measurements.
The Abbe-error-free design is explained using the example of a nanopositioning and nanomeasuring machine developed at the Institute of Process Measurement and Sensor Technology (Ilmenau University of Technology) and manufactured at the SIOS Meßtechnik GmbH Ilmenau, Germany.

The traditional control charts are based on the assumption that the measurement data relating to the average of each subgroup of the parameters under observation of a specific quality characteristic of product, process, system or service, are reported regardless of time stability of its own parameters. This condition is generally not verified in real cases, where we should take into account the lifecycle of measuring. In the case of monitoring of quality characteristic of a product for example, a parameter that is not in fact enjoy the property of time stability is its reliability, which is time-variant and it's decreasing over time in force of degradation to which the product is subject.
The traditional approach involves the construction of control charts with stationary limits, ignoring the possibility of an "adjustment" of those limits. This conceptual innovation determines the possibility of having an instrument to check, in a way as "tracking trajectory", modulated on possible changes of the measuring. These variations may, for example, be due to degradation of the detained characteristics. The modelling for the scenario described is based on the implementation of reliability function, as a known source of the variability of control limits, as pre-determinable through the lifecycle of the product analyzed.
The results achieved through the proposed approach can improve the sensitivity of the monitoring instrument through the modulation of control limits, which thus acquires a beneficial discriminatory capacity, able to separate the effects of random variability arising from the common causes, from those owned to deterministic variability related to predictable changes of the measuring.
Numerical results, regarding an application to a manufacturing national company operating in the automotive sector, through fielded units taken in differing operating periods and tested, are reported.

A very simple circuit for a 3-bits discrete pure linear analog preprocessing folding ADC is presented. The device is based on the folding idea: the DAC, the summing node and the amplifier, fundamental elements of the classical architecture, are eliminated and replaced with an analogical signal preprocessing parallel structure named "channels". All channels are connected as a cascade and only three transistors constitute each one. The circuit has been widely analyzed by simulation and its simplicity guarantees easiness of realization, reduction of power consumption and reduction of total conversion time, making it close to the ADC flash. A first discrete circuit it has been realized and tested.

Optical flats are required for spreading accuracy to mechanical and optical instruments, ordinarily by optical interference. Traceability of optical flats is ordinarily made by Fizeau interferometer. Traceability of this one requires higher accuracy flats, not available in secondary laboratories. These laboratories can accede to absolute self-calibration principles, by a method proposed by Bernard, who compares three flats among them through Zernike polynomials, representing these last their topographies.
Two problems are found when the process is intended to set up: (a) the Zernike polynomials have not easy geometric meaning and direct equivalence with CAD entities; (b) neither fringes nor levels of gray of interferograms have direct equivalences with the shape of flats or virtual membranes.
For modelling shapes we adopted the self calibration concept of Bernard, but using b-splines models with ring shape, instead Zernike. This substitution offer important algebraic simplifications and possibilities for exporting shapes to CAD; supporting validation.
For converting interferograms to shapes of membranes, three major problems are present: the aspect of patterns, the ambiguity in inflection areas, and the adequate interpretation of gray scales.
After applying low pass filters to brightness, two methods were applied: (a) heuristic genetic, (b) inverse sine correlation of gray for relief. Success in interpretation of shape have been by now better than 75%.