Extrusion is one of the widest used and the most basic processes of plastic forming, and the metal flow in extrusion is affected by many factors, such as friction, die shape, billet temperature and so on. Among these factors, friction is the key boundary condition to determine the property of the extruded products. In this paper research and measurements of velocity fields and impact of friction on velocity distribution in forward extruded specimens of copper alloy were analysed using the visioplasticity method. The visioplasticity method was used to find the complete velocity distributions from the experimental data by the finite-difference method. Comparison was made between velocity distributions in the specimens extruded with different lubricants with different coefficients of friction. The results in a form of diagrams have shown that the influence of the lubricant's coefficient of friction on the velocity distributions in extruded material can be of great importance especially in some critical regions in the cold formed material.

Information on physical image quality of medical images is important for imaging system assessment in order to promote and stimulate the development of state-of-the-art imaging systems. In this paper, we present a method for measuring physical performance of medical imaging systems. In this method, mutual information (MI) which is a concept from information theory was used to measure combined properties of image noise and resolution of an imaging system. In our study, the MI was used as a measure to express the amount of information that an output image contains about an input object. The more the MI value provides, the better the image quality is. To validate the proposed method, computer simulations were first performed to investigate the effects of noise and resolution degradation on the MI. Then experiments were conducted to measure the physical performance of an imaging plate which was used as an image detector. Our simulation and experimental results confirmed that the combined effect of deteriorated blur and noise on the images can be measured and analyzed using the MI metric. The results demonstrate the potential usefulness of the proposed method for measuring physical quality of medical imaging systems.

In the uncertainty budget of Rockwell C hardness (HRC) tests, geometric error of the Rockwell diamond indenter is a major contributor. The geometric calibration of Rockwell diamond indenters has been a key issue for Rockwell hardness standardization. The National Institute of Standards and Technology (NIST) developed a microform calibration system based on a stylus instrument for the geometric calibration of Rockwell diamond indenters. Using that system, a NIST master standard Rockwell diamond indenter No. 3581 was established in 1995, by which approximately 300 standard reference material (SRM) Rockwell hardness blocks of HRC scale were calibrated for implementation of the HRC scale in the United States. This indenter has been re-calibrated in 1997, 2005 and 2007. The calibration results have shown both high stability for the NIST standard Rockwell diamond indenter and high reproducibility for the NIST microform calibration system. After more than fifteen years of service, the stylus instrument was recently replaced by a new one. In order to test the measurement agreement between the two stylus instruments, another NIST master Rockwell diamond indenter No. 101 has been recently calibrated by the new instrument and the calibration result shows good agreement with the previous results.

The paper outlines the content and organisation of the generic concepts and principles of measurement and instrumentation. It argues that recent changes of technology and the political, economic and social environments demand a review of those principles and considers the resultant challenges and lines of advance. It distinguishes between measurement and instrument science. It considers the challenges presented by applications of measurement outside the physical sciences. It highlights the effect of advances in computing and the resultant convergence the principles of measurement and instrumentation and the sciences underlying systems and information. It considers special problems of sensing and actuation. It points to the design orientation of measurement and instrumentation principles and applications of the systems approach to measurement and instrumentation. It examines indirect measurement. Problems of errors and uncertainty are pointed out. Finally it points to the approaches of knowledge management.

Modern building technologies (for example prestressed concrete to produce beams, floors, bridges, or installation, testing and monitoring of ground anchors) require the use of accurate force machines (hydraulic jacks). One component of successful building works is a correct and accurate calibration procedure of hydraulic jack for tensioning cables or anchors. This article analyzes two different calibration methods: By means of hollow load cell and thread bar and calibration in the closed frame.
We analyze these methods using different accessories and their influence on the uncertainty of calibration results. As a very important part of calibration procedure is a correct choice of the calibration mathematical model (interpolation curve force-hydraulic pressure and hydraulic pressure-force), there is a need to use a special software. Such is the developed software FORCE-401-S which permits to communicate the measurement line "load cell-amplifier-computer"; to choose the correct interpolation polynom; enable to compute the errors and uncertainty values and build the table of calibration results.
The calibration procedure is performed according to the standard ISO 7500-1 "Verification of static uniaxial testing machines - Part 1: Tension/compression testing machines - Verification and calibration of the force-measuring system". We recommend to widen the definitions of this standard and to include calibration of non-force units scaled devices (as an example pressure gauges).